Electrical and Electronics Engineering publications abstract of: 05-2017 sorted by title, page: 4

» Burst-Erasure Correcting Codes With Optimal Average Delay
Abstract:
The objective of low-delay codes is to protect communication streams from erasure bursts by minimizing the time between the packet erasure and its reconstruction. Previous work has concentrated on the constant-delay scenario, where all erased packets need to exhibit the same decoding delay. We consider the case of heterogeneous delay, where the objective is to minimize the average delay across the erased packets in a burst. We derive delay lower bounds for the average case, and show that they match the constant-delay bounds only at a single rate point . We then construct codes with optimal average delays for the entire range of code rates. The construction for rates achieves optimality for every erasure instance, while the construction for rates is optimal for a fraction of all burst instances and close to optimal for the remaining fraction. The paper also studies the benefits of delay heterogeneity within the application of sensor communications. It is shown that a carefully designed code can significantly improve the temporal precision at the receiving node following erasure-burst events.
Autors: Nitzan Adler;Yuval Cassuto;
Appeared in: IEEE Transactions on Information Theory
Publication date: May 2017, volume: 63, issue:5, pages: 2848 - 2865
Publisher: IEEE
 
» C-Vine Copula Mixture Model for Clustering of Residential Electrical Load Pattern Data
Abstract:
The ongoing deployment of residential smart meters in numerous jurisdictions has led to an influx of electricity consumption data. This information presents a valuable opportunity to suppliers for better understanding their customer base and designing more effective tariff structures. In the past, various clustering methods have been proposed for meaningful customer partitioning. This paper presents a novel finite mixture modeling framework based on C-vine copulas (CVMM) for carrying out consumer categorization. The superiority of the proposed framework lies in the great flexibility of pair copulas toward identifying multidimensional dependency structures present in load profiling data. CVMM is compared to other classical methods by using real demand measurements recorded across 2613 households in a London smart-metering trial. The superior performance of the proposed approach is demonstrated by analyzing four validity indicators. In addition, a decision tree classification module for partitioning new consumers is developed and the improved predictive performance of CVMM compared to existing methods is highlighted. Further case studies are carried out based on different loading conditions and different sets of large numbers of households to demonstrate the advantages and to test the scalability of the proposed method.
Autors: Mingyang Sun;Ioannis Konstantelos;Goran Strbac;
Appeared in: IEEE Transactions on Power Systems
Publication date: May 2017, volume: 32, issue:3, pages: 2382 - 2393
Publisher: IEEE
 
» Calibration of Nonlinear Crosstalk in MIMO Transmitter
Abstract:
Multiple-input multiple-output (MIMO) techniques have been extensively used in modern wireless communications. The front-end nonlinearity coupled with crosstalk in a MIMO transmitter is much more complex than that in a single-input single-output (SISO) system. In this paper, we propose a nonlinear crosstalk calibration algorithm with the corresponding reference signal design. We start with the nonlinear crosstalk model of the MIMO transmitter and derive its corresponding inverse compensation model. The proposed model characterizes the nonlinearity and the crosstalk in separated blocks. We then propose specifically designed reference signals that utilize the model structure. The nonlinear crosstalk model can be reorganized and simplified with the reference signal. Thus, the complexity of the model coefficients estimation is greatly reduced without compromising the model accuracy. In addition, with the proposed algorithm, the compensation of the nonlinearity and crosstalk can be done separately. Simulations show a satisfactory calibration results with low computational complexity.
Autors: Hua Qian;Xin Cheng;Xiliang Luo;Weifeng Feng;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: May 2017, volume: 66, issue:5, pages: 3739 - 3748
Publisher: IEEE
 
» Camera Self-Calibration Based on Nonlinear Optimization and Applications in Surveillance Systems
Abstract:
This paper presents a new approach for self-calibration of static cameras in the context of surveillance applications. Initially, a pedestrian detector is applied and the responses are validated using background removal. Then, foreground-related pixels within the detection results are used to estimate the feet-head line segments of each person (called poles), which are used to find a linear estimate for the camera matrix. Finally, a nonlinear cost function is used to refine the initial estimate, aiming to mostly improve the orientation of the reprojected poles. We also present different applications of self-calibration in tasks related to video surveillance itself, such as improvements to pedestrian detection and tracking algorithms, and augmented reality applications, such as the insertion of virtual cameras to aid the placement of real cameras in the scene.
Autors: Gustavo Führ;Cláudio Rosito Jung;
Appeared in: IEEE Transactions on Circuits and Systems for Video Technology
Publication date: May 2017, volume: 27, issue:5, pages: 1132 - 1142
Publisher: IEEE
 
» Can Affective Computing Save Lives? Meet Mobile Health
Abstract:
This installment of Computer's series highlighting the work published in IEEE Computer Society journals comes from IEEE Transactions on Affective Computing.
Autors: Björn Schuller;
Appeared in: Computer
Publication date: May 2017, volume: 50, issue:5, pages: 13 - 13
Publisher: IEEE
 
» Capabilities of CdTe-Based Detectors With ${mathrm {MoO}}_{x}$ Contacts for Detection of X- and $gamma$ -Radiation
Abstract:
The charge transport mechanism and spectrometric properties of the X-ray and -ray detectors, fabricated by the deposition of molybdenum oxide thin films onto semi-insulating p-CdTe crystals were studied. The current transport processes in the structure are well described in the scope of the carrier’s generation in the space-charge region and the space-charge-limited current models. The lifetime of charge carriers, the energy of hole traps, and the density of discrete trapping centers were determined from the comparison of the experimental data and calculations. Spectrometric properties of structures were also investigated. It is shown that the investigated heterojunctions have demonstrated promising characteristics for practical application in X-ray and -ray detector fabrication.
Autors: O. L. Maslyanchuk;M. M. Solovan;V. V. Brus;V. V. Kulchynsky;P. D. Maryanchuk;I. M. Fodchuk;V. A. Gnatyuk;T. Aoki;C. Potiriadis;Y. Kaissas;
Appeared in: IEEE Transactions on Nuclear Science
Publication date: May 2017, volume: 64, issue:5, pages: 1168 - 1172
Publisher: IEEE
 
» Capacity Analysis of FBMC-OQAM Systems
Abstract:
This letter presents a capacity analysis of filter bank multicarrier offset quadrature amplitude modulation (FBMC-OQAM) systems. In FBMC-OQAM receivers, it is common to preserve the real part of the demodulated signal samples for information recovery. The imaginary part of these samples, which are called intrinsic interference, is simply ignored. This letter provides a theoretical answer to the following fundamental question. Does the ignored imaginary interference in FBMC-OQAM contain any information beyond what could be obtained from the preserved real parts?
Autors: Ahmad RezazadehReyhani;Behrouz Farhang-Boroujeny;
Appeared in: IEEE Communications Letters
Publication date: May 2017, volume: 21, issue:5, pages: 999 - 1002
Publisher: IEEE
 
» Capacity Bounds for the Gaussian IM-DD Optical Multiple-Access Channel
Abstract:
Optical wireless communications (OWC) is a promising technology for closing the mismatch between the growing number of connected devices and the limited wireless network capabilities. Similar to downlink, uplink can also benefit from OWC for establishing connectivity between such devices and an optical access point. In this context, the incoherent intensity-modulation and direct-detection (IM-DD) scheme is desirable in practice. Hence, it is important to understand the fundamental limits of communication rates over an OWC uplink employing IM-DD, i.e., the channel capacity. This uplink, modeled as a Gaussian multiple-access channel (MAC) for indoors OWC, is studied in this paper, under the IM-DD constraints, which form the main difference with the standard Gaussian MAC commonly studied in the radio-frequency context. Capacity region outer and inner bounds for this channel are derived. The bounds are fairly close at high signal-to-noise ratio (SNR), where a truncated-Gaussian input distribution achieves the capacity region within a constant gap. Furthermore, the bounds coincide at low SNR showing the optimality of ON–OFF keying combined with successive cancellation decoding in this regime. At moderate SNR, an optimized uniformly spaced discrete input distribution achieves fairly good performance.
Autors: Anas Chaaban;Omer Mahmoud S. Al-Ebraheemy;Tareq Y. Al-Naffouri;Mohamed-Slim Alouini;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: May 2017, volume: 16, issue:5, pages: 3328 - 3340
Publisher: IEEE
 
» Carbon Nanotube Interconnects for Nanoelectronic Integrated Systems
Abstract:
A perspective study about the effect of carbon nanotube compared with copper interconnects in the H-tree distributed clock network - used for routing clock signals inside a chip - in nanoelectronic systems will be developed based on simulation models. Important features for circuit design, such as low logic level, high logic level, rise time, slew rate, attenuation, delay time, dissipated power and delay-power product will be evaluated by computer simulations. Results will show that distributed networks based on carbon nanotube interconnects are able to operate at terahertz frequencies.
Autors: Camila Peixoto da Silva Madeira Nogueira;Janaina Goncalves Guimaraes;
Appeared in: IEEE Latin America Transactions
Publication date: May 2017, volume: 15, issue:5, pages: 813 - 818
Publisher: IEEE
 
» Cardiac Image Reconstruction via Nonlinear Motion Correction Based on Partial Angle Reconstructed Images
Abstract:
Even though the X-ray Computed Tomography (CT) scan is considered suitable for fast imaging, motion-artifact-free cardiac imaging is still an important issue, because the gantry rotation speed is not fast enough compared with the heart motion. To obtain a heart image with less motion artifacts, a motion estimation (ME) and motion compensation (MC) approach is usually adopted. In this paper, we propose an ME/MC algorithm that can estimate a nonlinear heart motion model from a sinogram with a rotation angle of less than 360°. In this algorithm, we first assume the heart motion to be nonrigid but linear, and thereby estimate an initial 4-D motion vector field (MVF) during a half rotation by using conjugate partial angle reconstructed images, as in our previous ME/MC algorithm. We then refine the MVF to determine a more accurate nonlinear MVF by maximizing the information potential of a motion-compensated image. Finally, MC is performed by incorporating the determined MVF into the image reconstruction process, and a time-resolved heart image is obtained. By using a numerical phantom, a physical cardiac phantom, and an animal data set, we demonstrate that the proposed algorithm can noticeably improve the image quality by reducing motion artifacts throughout the image.
Autors: Seungeon Kim;Yongjin Chang;Jong Beom Ra;
Appeared in: IEEE Transactions on Medical Imaging
Publication date: May 2017, volume: 36, issue:5, pages: 1151 - 1161
Publisher: IEEE
 
» Catch the Wave! [From the Guest Editors' Desk]
Abstract:
Autors: Aditya Singh;Isar Mostafanezhad;
Appeared in: IEEE Microwave Magazine
Publication date: May 2017, volume: 18, issue:3, pages: 12 - 14
Publisher: IEEE
 
» Causal Boxes: Quantum Information-Processing Systems Closed Under Composition
Abstract:
Complex information-processing systems, for example, quantum circuits, cryptographic protocols, or multi-player games, are naturally described as networks composed of more basic information-processing systems. A modular analysis of such systems requires a mathematical model of systems that is closed under composition, i.e., a network of these objects is again an object of the same type. We propose such a model and call the corresponding systems causal boxes. Causal boxes capture superpositions of causal structures, e.g., messages sent by a causal box can be in a superposition of different orders or in a superposition of being sent to box and box . Furthermore, causal boxes can model systems whose behavior depends on time. By instantiating the abstract cryptography framework with causal boxes, we obtain the first composable security framework that can handle arbitrary quantum protocols and relativistic protocols.
Autors: Christopher Portmann;Christian Matt;Ueli Maurer;Renato Renner;Björn Tackmann;
Appeared in: IEEE Transactions on Information Theory
Publication date: May 2017, volume: 63, issue:5, pages: 3277 - 3305
Publisher: IEEE
 
» Cellular Offloading in Heterogeneous Mobile Networks With D2D Communication Assistance
Abstract:
The next-generation mobile communication system [fifth-generation (5G)] needs to address the challenges stemming from the performance requirements in diverse technical scenarios, such as seamless wide-area coverage, high-capacity hot-spots, and low-power massive connections. It is widely recognized that traditional single-tier cellular network architecture is not adequate to meet these requirements, and thus, the heterogeneous cellular network (HetNet) has been identified as a promising network architecture for 5G. In HetNets, traffic offloading can be exploited to effectively improve network capacity by utilizing complementary network communication techniques. In this paper, we propose a device-to-device (D2D) communication assisted mobile traffic offloading (DATO) scheme, with focus on massive connections for machine type communications (MTC). DATO determines access mode for user equipments (UEs) to offload UEs from macro base stations (MBSs) to small base stations via D2D communications to improve the overall network capacity and mitigate the traffic congestion at MBSs. We formulate the DATO problem as a 0–1 linear programing and prove it to be NP-hard. We resort to dynamic programing to provide the optimal solution, as well as the theoretical performance upper bound of DATO. We develop an efficient algorithm to solve the DATO problem while preserving the optimality by making use of the location relationship of BSs and UEs. We apply our proposed DATO scheme to a series of typical network scenarios to validate its effectiveness. Numerical results reveal that DATO significantly outperforms traditional UE access mode in terms of network capacity and UE energy consumption, which are important to massive MTC.
Autors: Wei Cao;Gang Feng;Shuang Qin;Mu Yan;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: May 2017, volume: 66, issue:5, pages: 4245 - 4255
Publisher: IEEE
 
» Centralized Collaborative Sparse Unmixing for Hyperspectral Images
Abstract:
Spectral unmixing is very important in hyperspectral image analysis and processing, which aims at identifying the constituent spectra (i.e., endmembers) and estimating their fractional abundances from the mixed pixels. In recent years, sparse unmixing has received considerable interest. However, the acquired hyperspectral images are generally degraded by the noise, making sparse unmixing not faithful enough. To address this issue, this paper proposes a novel framework to couple sparse hyperspectral unmixing and abundance estimation error reduction together. Specifically, with the definition of abundance estimation error, a centralized constraint is incorporated into the collaborative sparse unmixing framework by exploiting the nonlocal redundancy of abundance map. This way we suppress the abundance estimation error, and improve the unmixing accuracy. Meanwhile, the alternating direction method of multipliers is introduced to solve the underlying constrained model. Experimental results on both synthetic and real hyperspectral data demonstrate the effectiveness of our proposed algorithm.
Autors: Rui Wang;Heng-Chao Li;Wenzhi Liao;Xin Huang;Wilfried Philips;
Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Publication date: May 2017, volume: 10, issue:5, pages: 1949 - 1962
Publisher: IEEE
 
» Change Detection Based on Gabor Wavelet Features for Very High Resolution Remote Sensing Images
Abstract:
In this letter, we propose a change detection method based on Gabor wavelet features for very high resolution (VHR) remote sensing images. First, Gabor wavelet features are extracted from two temporal VHR images to obtain spatial and contextual information. Then, the Gabor-wavelet-based difference measure (GWDM) is designed to generate the difference image. In GWDM, a new local similarity measure is defined, in which the Markov random field neighborhood system is incorporated to obtain a local relationship, and the coefficient of variation method is applied to discriminate contributions from different features. Finally, the fuzzy c-means cluster algorithm is employed to obtain the final change map. Experiments employing QuickBird and SPOT5 images demonstrate the effectiveness of the proposed approach.
Autors: Zhenxuan Li;Wenzhong Shi;Hua Zhang;Ming Hao;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: May 2017, volume: 14, issue:5, pages: 783 - 787
Publisher: IEEE
 
» Changes to the Editorial Board
Abstract:
It is my pleasure to welcome Dr. Brian S. Doyle to the Editorial Board of the IEEE Electron Device Letters. A biography and sketch of Dr. Doyle’s research interests can be found below. His subject areas are Emerging Technologies and Devices and Embedded Memory Devices and Technology.
Autors: Tsu-Jae King Liu;
Appeared in: IEEE Electron Device Letters
Publication date: May 2017, volume: 38, issue:5, pages: 539 - 539
Publisher: IEEE
 
» Changing Lives in EPICS Fashion
Abstract:
Founded at Purdue University in 1995, Engineering Projects in Community Service (EPICS) in IEEE empowers teams of university and high school students to collaborate on socially innovative projects that will have a lasting impact on local humanitarian organizations and community members. Not only does this program give students a unique platform to experience a career in the engineering field, which many of them are already pursuing, but it also enables them to develop and broaden their technical skills to address critical community issues while transforming lives.
Autors: Lindsey Moses;
Appeared in: IEEE Potentials
Publication date: May 2017, volume: 36, issue:3, pages: 6 - 17
Publisher: IEEE
 
» Channel Correlation Modeling and its Application to Massive MIMO Channel Feedback Reduction
Abstract:
In this paper, we propose a feedback information reduction technique for massive multiple-input multiple-output (MIMO) systems. To this end, we analytically derive a covariance matrix of spatially correlated Rayleigh fading channels in closed form. The covariance matrix is expressed based on its statistics, including transmit and receive antennas’ correlation factors, channel variance, and channel delay profile. The closed-form expression enables a principal component analysis (PCA)-based compression of channel state information (CSI), which allows the feedback overhead to be efficiently reduced. We also analyze the compression feedback error, bit-error-rate (BER) performance, and the spectral efficiency (SE) of the system using the PCA-based compression. Under our proposed model, numerical results verify that the PCA-based compression method significantly reduces the feedback overhead of the massive MIMO systems with marginal performance degradation from full-CSI feedback. Furthermore, we propose a new design framework by numerically showing that there exists the optimal number of transmit antennas in terms of SE for a given limited feedback amount.
Autors: Jingon Joung;Ernest Kurniawan;Sumei Sun;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: May 2017, volume: 66, issue:5, pages: 3787 - 3797
Publisher: IEEE
 
» Channel Selection Algorithm for Cognitive Radio Networks with Heavy-Tailed Idle Times
Abstract:
We consider a multichannel Cognitive Radio Network (CRN), where secondary users sequentially sense channels for opportunistic spectrum access. In this scenario, the Channel Selection Algorithm (CSA) allows secondary users to find a vacant channel with the minimal number of channel switches. Most of the existing CSA literature assumes exponential ON-OFF time distribution for primary user's (PU) channel occupancy pattern. This exponential assumption might be helpful to get performance bounds; but not useful to evaluate the performance of CSA under realistic conditions. An in-depth analysis of independent spectrum measurement traces reveals that wireless channels have typically heavy-tailed PU OFF times. In this paper, we propose an extension to the Predictive CSA framework and its generalization for heavy tailed PU OFF time distribution, which represents realistic scenarios. In particular, we calculate the probability of channel being idle for hyper-exponential OFF times to use in CSA. We implement our proposed CSA framework in a wireless test-bed and comprehensively evaluate its performance by recreating the realistic PU channel occupancy patterns. The proposed CSA shows significant reduction in channel switches and energy consumption as compared to Predictive CSA which always assumes exponential PU ON-OFF times. Through our work, we show the impact of the PU channel occupancy pattern on the performance of CSA in multichannel CRN.
Autors: Senthilmurugan Sengottuvelan;Junaid Ansari;Petri Mähönen;T.G. Venkatesh;Marina Petrova;
Appeared in: IEEE Transactions on Mobile Computing
Publication date: May 2017, volume: 16, issue:5, pages: 1258 - 1271
Publisher: IEEE
 
» Channel-Aware Polling-Based MAC Protocol for Body Area Networks: Design and Analysis
Abstract:
Body area networks (BANs) enable wearable/implanted devices to exchange information or collect monitored data. The channel quality of a link in a BAN is typically highly dynamic, since sensors equipped on a human body usually move with gesture, posture, or mobility. Therefore, existing sleep-wake-up scheduling mechanisms used in traditional static sensor networks could be very inefficient in a BAN, because they do not consider channel fluctuation of body sensors. Sensors might be waked up to transmit during bad channel conditions, leading to transmission failures and energy waste. To remedy this inefficiency, this paper proposes a Channel-aware Polling-based MAC protocol CPMAC. Our design only wakes sensors up and triggers them to transmit when the channel is strong enough to ensure fast and reliable transmissions. We further analyze the energy consumption and derive a queueing model to estimate the probability of completing all data transmissions of all sensors in our CPMAC. Benefiting from these analyses, we are able to optimize energy efficiency of our CPMAC by adapting the number of polling periods in a superframe to dynamic traffic demands and channel fluctuation. Our simulation results show that, as compared with TDMA-based scheduling and the IEEE 802.15.6 CSMA/CA protocol, CPMAC significantly improves energy efficiency and, meanwhile, keeps the latency short.
Autors: Chi-Han Lin;Kate Ching-Ju Lin;Wen-Tsuen Chen;
Appeared in: IEEE Sensors Journal
Publication date: May 2017, volume: 17, issue:9, pages: 2936 - 2948
Publisher: IEEE
 
» Characteristic Mode Analysis of Plasmonic Nanoantennas
Abstract:
The theory of characteristic modes (TCMs) based on the surface integral equation (SIE) formalism is presented for the analysis of plasmonic nanostructures. With TCM, excitation-independent characteristic solutions of the underlying electromagnetic field problem are obtained. Both single and multiple particle nanostructures are analyzed using the conventional SIE approach and the TCM formalism. By comparing these results, the modes that are responsible of the observed scattering and absorption characteristics can be identified. These solutions can be further utilized in the design and tuning nanoantenna configurations for specific application purposes.
Autors: Pasi Ylä-Oijala;Dimitrios C. Tzarouchis;Elias Raninen;Ari Sihvola;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: May 2017, volume: 65, issue:5, pages: 2165 - 2172
Publisher: IEEE
 
» Characteristics of Needle-Disk Electrodes Atmospheric Pressure Discharges Applied to Modify PET Wettability
Abstract:
In the atmospheric pressure discharge with arran- gement of a syringe needle, a capillary, and an external disk, it was observed different operation modes according to the relative position of the electrodes. With external electrode over the shaft of the needle, a stable and steady plume is formed from the tip of the needle to the exterior of the capillary. The breakdown is governed by filamentary discharges that evolve randomly on time in the gap between the needle and the capillary. This mechanism changes to bullet-like discharge when the external disk is located off needle. The breakdown generates a large amount of charge that rises quickly and varies with the distance between the electrodes. The mean power is higher than that of the previous case and the plume generated, in interaction with external metallic surface, is more unstable to arc transition. Independently of the operation mode, high electric field at the bevel of the needle plays an important role on the evolution of the plume. The application of the plume to change the wettability properties of the polyethylene terephthalate indicated rapid augment of the hydrophilicy and treated area larger than the plume dimension.
Autors: Milton Eiji Kayama;Lucas José da Silva;Vadym Prysiazhnyi;Konstantin G. Kostov;Mauricio Antonio Algatti;
Appeared in: IEEE Transactions on Plasma Science
Publication date: May 2017, volume: 45, issue:5, pages: 843 - 848
Publisher: IEEE
 
» Characterization and Optimization of Unrepeatered Coherent Transmission Systems Using DRA and ROPA
Abstract:
We present a detailed investigation of the singe-channel 100G polarization-multiplexed quadrature-phase-shift-keying-based unrepeatered coherent transmissions using various order distributed Raman amplifiers (DRAs). The impact of main factors on the system performance is discussed including intrachannel nonlinearity, amplified spontaneous emission, double Rayleigh backscattering, and pump relative intensity noise (RIN)-induced impairments. After optimizing the pump power configuration, it is found that compared to a first- and a third-order DRA, a second-order DRA can provide the best performance owing to relative high optical signal-to-noise ratio (OSNR) and low pump RIN-induced penalty. By using the Giles model, the optimization of a remote optically pumped amplifier is performed in terms of the Erbium-doped fiber length and its farthest position, with given input signal's power and OSNR.
Autors: Jingchi Cheng;Ming Tang;Songnian Fu;Perry Ping Shum;Deming Liu;
Appeared in: Journal of Lightwave Technology
Publication date: May 2017, volume: 35, issue:10, pages: 1830 - 1836
Publisher: IEEE
 
» Characterization of Defects in AlGaN/GaN HEMTs Based on Nonlinear Microwave Current Transient Spectroscopy
Abstract:
This paper presents a new nonlinear microwave-based characterization methodology for the study of the deep levels proprieties in gallium nitride (GaN)-based high electron mobility transistors (HEMTs). Currently, it is unique measurement method allowing the extraction of time constants of HEMTs operating under large signal RF conditions. This method improves the conventional dc techniques, since it employs RF excitation during the filling condition to investigate the impact of “real-life” RF excitation on the trapping mechanisms. The experimental results demonstrate that, beyond the presence of Poole–Frenkel effect, the slow detrapping time constant is accelerated by the power dissipation of the trapping bias point. Moreover, it is possible to distinguish the impact of dc and RF conditions on the trapping phenomena. The temperature measurements allow identifying the 0.75-eV deep level, attributed to extended defects in GaN, when ionized under dc excitation. This deep level trap is probably located in the buffer layer and contributes to the RF trapping phenomenon.
Autors: Agostino Benvegnù;Sylvain Laurent;Olivier Jardel;Jean-Luc Muraro;Matteo Meneghini;Denis Barataud;Gaudenzio Meneghesso;Enrico Zanoni;Raymond Quéré;
Appeared in: IEEE Transactions on Electron Devices
Publication date: May 2017, volume: 64, issue:5, pages: 2135 - 2141
Publisher: IEEE
 
» Characterization of Iron Loss for Integral-Slot Interior Permanent Magnet Synchronous Machine During Flux Weakening
Abstract:
Iron loss resistance is widely used for rapid motor design and maximum efficiency control. However, the harmonic loss obviously increases during flux weakening, and even dominates in total iron loss, especially in deep flux weakening region. This paper presents an analytical calculation method of iron loss for an integral-slot interior permanent magnet synchronous machine (IPMSM) by iron loss resistance, considering harmonic effect during flux weakening. To predict the harmonic loss, both a harmonic loss voltage and a harmonic loss coefficient are employed into an iron loss resistance model, and the relation of harmonic loss to the harmonic voltage and coefficient are studied. The iron loss and efficiency of an integral-slot IPMSM are, respectively, obtained by the proposed model, the conventional model, the experiment, and finite-element analysis (FEA). The proposed model is validated by the comparison with FEA and experimental results.
Autors: Qi Li;Tao Fan;Xuhui Wen;
Appeared in: IEEE Transactions on Magnetics
Publication date: May 2017, volume: 53, issue:5, pages: 1 - 8
Publisher: IEEE
 
» Characterization of the Spatial Variability of In-Situ Soil Moisture Measurements for Upscaling at the Spatial Resolution of RADARSAT-2
Abstract:
This study characterizes the spatial variability of soil moisture measurements using statistical and geostatistical analyses for the transferability of the ground measurements to the scale of the spatial resolution of RADARSAT-2 images. It aims to better interpret synthetic aperture radar backscattering relationships to soil moisture. Coincident with RADARSAT-2 overpasses, soil and crop parameters were measured in July 2008 and August 2009 over two Canadian agricultural sites (Kenaston, Saskatchewan, and Lennoxville, Québec). The measured soil moisture was used to determine the theoretical semivariogram models that fit the experimental semivariograms. An inverse correlation is obtained between the soil moisture coefficient of variation (CV) and the range (spatial correlation) of the semivariogram, which can assess the degree of the spatial correlation between the samples of each field. Soil moisture measurements with high values of CV (20%–40%) are correlated within a distance less than 10 m and those with lower CV (10%–20%) are correlated within a larger distance varying between 12 and 46 m. The soil moisture measurements of each field were upscaled to the spatial resolution of RADARSAT-2 images ( and ) using either simple kriging or ordinary kriging. The results were cross validated using the surface scattering component, which is extracted from the Freeman–Durden decomposition applied to fully polarimetric RADARSAT-2 images. They show that the kriging-based soil moisture better represents RADARSAT-2 surface scattering with strong clustered linear regressions (R2 greater than ∼0.6, RMSE lower than ∼0.9 dB, and p-value of slope less than 0.05) than the nonkriged soil moisture samples.
Autors: Imen Gherboudj;Ramata Magagi;Aaron A. Berg;Brenda Toth;
Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Publication date: May 2017, volume: 10, issue:5, pages: 1813 - 1823
Publisher: IEEE
 
» Characterizing the Instantaneous Connectivity of Large-Scale Urban Vehicular Networks
Abstract:
Understanding of the network topology is a basic building block towards the design of efficient networking solutions. In the context of vehicular networks, such a step is especially crucial due to the highly dynamic nature of vehicles that can lead to strong instantaneous variations in the structure of the network. This notwithstanding, and despite the soon-to-come real-world deployment of vehicle-to-vehicle communication technologies, we still lack a clear understanding of vehicular network topological properties. In this paper, we present a complex network analysis of the instantaneous topology of a realistic vehicular network in Cologne, Germany. Our study unveils a poorly connected topology, with very limited availability, reliability, and navigability. We also examine the vehicular network topology in a second scenario, i.e., Zurich, Switzerland. The comparative analysis shows how simplistic mobility models can lead to unrealistic overly connected topologies.
Autors: Diala Naboulsi;Marco Fiore;
Appeared in: IEEE Transactions on Mobile Computing
Publication date: May 2017, volume: 16, issue:5, pages: 1272 - 1286
Publisher: IEEE
 
» Choosing Bootstrap Method for the Estimation of the Uncertainty of Traffic Noise Measurements
Abstract:
The environmental acoustic noise is considered as a big risk for today’s population health. Consequently, the regulations in many countries commit themselves to control the exposition of people, imposing limits to the noise level. In the comparison between the measured value and the threshold, the uncertainty of the measured value has to be taken into account. In this paper, a procedure for the evaluation of the uncertainty of traffic noise measurements due to the variability of the measurand is proposed. A deep analysis of five bootstrap (normal, basic percentile, t-student, bias corrected percentile, and bias corrected and accelerated percentile) methods is performed to obtain accurate confidence intervals for the indicator without necessity to make normal theory assumptions. From the comparison with the classical method (according to Guide to the Expression of Uncertainty in Measurement (ISO GUM)), the novel approach reveals to be more effective for estimating both the expected value and the uncertainty of the short-term equivalent sound pressure level when a large data set is not available.
Autors: Consolatina Liguori;Alessandro Ruggiero;Paolo Sommella;Domenico Russo;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: May 2017, volume: 66, issue:5, pages: 869 - 878
Publisher: IEEE
 
» Ciphertext-Only Attack on Linear Feedback Shift Register-Based Esmaeili-Gulliver Cryptosystem
Abstract:
Esmaeili and Gulliver recently proposed a secret key cryptosystem based on error-correcting codes in which a codeword modified by random insertions, deletions, and errors is used as a ciphertext. The secret keys used in this cryptosystem consist of random numbers generated by synchronized random number generators that are implemented using two distinct linear feedback shift registers (LFSRs) in each encryptor and decryptor, respectively. In this letter, we propose a ciphertext-only attack to break the Esmaeili-Gulliver cryptosystem based on LFSRs. The proposed attack requires consecutive ciphertexts, where is the number of shift registers in the LFSR, which is the secret key size. The proposed attack consists of two steps, and the time complexity of the first step is linear in the secret key size while the second step is a polynomial-time algorithm.
Autors: Yongwoo Lee;Young-Sik Kim;Jong-Seon No;
Appeared in: IEEE Communications Letters
Publication date: May 2017, volume: 21, issue:5, pages: 971 - 974
Publisher: IEEE
 
» Circuit Designs of High-Performance and Low-Power RRAM-Based Multiplexers Based on 4T(ransistor)1R(RAM) Programming Structure
Abstract:
Routing multiplexers based on pass-transistors or transmission gates are an essential components in many digital integrated circuits. However, whatever structure is employed, CMOS multiplexers have two major limitations: 1) their delay is linearly related to the input size; 2) their performance degrades seriously when operated in near- regime. Resistive Random Access Memory (RRAM) technology brings opportunities of overcoming these limitations by exploiting the properties of RRAMs and associated programming structures. In this paper, we propose new one-level, two-level and tree-like multiplexers circuit designs using 4T(ransistors)1R(RAM) elements and we compare them to naive one-level multiplexers. We consider the main physical design aspects associated with 4T1R-based multiplexers, such as the layout implications using a 7 nm FinFET technology, and the co-integration of low-voltage nominal power supply and high-voltage programming supply. Electrical simulations show that using a 7 nm FinFET transistor technology, the proposed 4T1R-based multiplexers reduce delay by and energy by over naive 4T1R and 2T1R counterparts. At nominal working voltage, considering an input size ranging from 2 to 50, the proposed 4T1R-based multiplexers reduces Area-Delay and Power-Delay products by and respectively, as compared to best CMOS multiplexers. In the near- regime, the proposed 4T1R-based multiplexer demonstrates larger delay efficiency over the best CMOS multiplexer. The proposed 4T1R-based multiplexers operating at near- regime can still achieve up to 22% delay improvement when compared to best CMOS multiplexers working at nominal voltage.
Autors: Xifan Tang;Edouard Giacomin;Giovanni De Micheli;Pierre-Emmanuel Gaillardon;
Appeared in: IEEE Transactions on Circuits and Systems I: Regular Papers
Publication date: May 2017, volume: 64, issue:5, pages: 1173 - 1186
Publisher: IEEE
 
» Circuit Implementation of Data-Driven TSK-Type Interval Type-2 Neural Fuzzy System With Online Parameter Tuning Ability
Abstract:
This paper proposes a new circuit for implementing a reduced-interval type-2 neural fuzzy system using weighted bound-set boundaries (RIT2NFS-WB) with online tuning ability. The antecedent and consequent parts of the RIT2NFS-WB use interval type-2 fuzzy sets and Takagi-Sugeno-Kang (TSK) rules with interval combination parameters, respectively. In the software implementation, the structure and parameters of the RIT2NFS-WB are learned through firing-strength-based rule generation and gradient descent algorithms, respectively. The software-designed RIT2NFS-WB is then transferred to a circuit implementation with online parameter-tuning ability; the hardware version is called the RIT2NFS-WB(HL). The RIT2NFS-WB(HL) is characterized by its online tuning ability with updatable consequent and weighting parameters. To the best of our knowledge, the RIT2NFS-WB(HL) is the first TSK-type interval type-2 neural fuzzy circuit with online parameter tuning ability in the literature. To take advantage of the inherent parallel processing property of the rules, a parallel processing technique is utilized in the RIT2NFS-WB(HL) to achieve computational speedup. The RIT2NFS-WB(HL) is applied to examples of online system modeling and sequence prediction to demonstrate the system's functionality.
Autors: Chia-Feng Juang;Kai-Jie Juang;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: May 2017, volume: 64, issue:5, pages: 4266 - 4275
Publisher: IEEE
 
» CIS Publication Spotlight [Publication Spotlight]
Abstract:
Presents a synopsis of the latest books in the area of computational intelligence.
Autors: Haibo He;Jon Garibaldi;Kay Chen Tan;Graham Kendall;Yaochu Jin;Yew Soon Ong;
Appeared in: IEEE Computational Intelligence Magazine
Publication date: May 2017, volume: 12, issue:2, pages: 20 - 22
Publisher: IEEE
 
» Classification and Prediction of Clinical Improvement in Deep Brain Stimulation From Intraoperative Microelectrode Recordings
Abstract:
We present a random forest (RF) classification and regression technique to predict, intraoperatively, the unified Parkinson's disease rating scale (UPDRS) improvement after deep brain stimulation (DBS). We hypothesized that a data-informed combination of features extracted from intraoperative microelectrode recordings (MERs) can predict the motor improvement of Parkinson's disease patients undergoing DBS surgery. We modified the employed RFs to account for unbalanced datasets and multiple observations per patient, and showed, for the first time, that only five neurophysiologically interpretable MER signal features are sufficient for predicting UPDRS improvement. This finding suggests that subthalamic nucleus (STN) electrophysiological signal characteristics are strongly correlated to the extent of motor behavior improvement observed in STN-DBS.
Autors: Kyriaki Kostoglou;Konstantinos P. Michmizos;Pantelis Stathis;Damianos Sakas;Konstantina S. Nikita;Georgios D. Mitsis;
Appeared in: IEEE Transactions on Biomedical Engineering
Publication date: May 2017, volume: 64, issue:5, pages: 1123 - 1130
Publisher: IEEE
 
» Classification of Three Types of Walking Activities Regarding Stairs Using Plantar Pressure Sensors
Abstract:
In this letter, we propose a novel method for classifying ambulatory activities using eight plantar pressure sensors within smart shoes. Using these sensors, pressure data of participants can be collected regarding level walking, stair descent, and stair ascent. Analyzing patterns of the ambulatory activities, we present new features with which to describe the ambulatory activities. After selecting critical features, a multi-class support vector machine algorithm is applied to classify these activities. Applying the proposed method to the experimental database, we obtain recognition rates up to 95.2% after six steps.
Autors: Gu-Min Jeong;Phuc Huu Truong;Sang-Il Choi;
Appeared in: IEEE Sensors Journal
Publication date: May 2017, volume: 17, issue:9, pages: 2638 - 2639
Publisher: IEEE
 
» Closed-Form BER Expressions for HSV-Based ${M}$ PSK-CSK Systems
Abstract:
The analysis of hybrid phase shift keying-color shift keying (PSK-CSK) systems under the additive white Gaussian noise model is presented. PSK-CSK systems are formed by mapping phase shift keying symbols to color shift keying using hue-saturation-value color space. Analytical expressions of bit error rate are given for , 4, 8, and 16, to validate the simulation results published previously.
Autors: Alain Richard Ndjiongue;Thokozani Shongwe;Hendrik C. Ferreira;
Appeared in: IEEE Communications Letters
Publication date: May 2017, volume: 21, issue:5, pages: 1023 - 1026
Publisher: IEEE
 
» Cloud Computing
Abstract:
Technologies and market players will change over time, but the bottom line is that cloud computing is here to stay.
Autors: Grace A. Lewis;
Appeared in: Computer
Publication date: May 2017, volume: 50, issue:5, pages: 8 - 9
Publisher: IEEE
 
» CloudScout: A Non-Intrusive Approach to Service Dependency Discovery
Abstract:
Nowadays, numerous enterprises are migrating their applications into cloud computing environments. Typically, the applications are composed of several dependent service components that span many hosts and network devices. In light of this, exploring the dependency between service components can be beneficial for achieving fast network application response time. Moreover, it is significant to consolidate service components according to resource constraints, service dependency, and network structure. However, it is a tedious task to discover the dependency among service components without expert knowledge of the running application. In this paper, we propose CloudScout, a non-intrusive approach that is capable of automatically discovering dependent service components. CloudScout analyzes the correlation among service components based on the time-series information from system monitoring logs. We address two key challenges in CloudScout: service distance calculation and dependent service clustering. We conduct experiments on five applications with 290 service components that span 20 physical hosts across two data centers. The experimental results demonstrate that CloudScout can successfully discover the dependency among service components and facilitate reducing the network latency of network applications and distributed applications.
Autors: Jianwei Yin;Xinkui Zhao;Yan Tang;Chen Zhi;Zuoning Chen;Zhaohui Wu;
Appeared in: IEEE Transactions on Parallel and Distributed Systems
Publication date: May 2017, volume: 28, issue:5, pages: 1271 - 1284
Publisher: IEEE
 
» Clutch Judder Classification and Prediction: A Multivariate Statistical Analysis Based on Torque Signals
Abstract:
Judder is the term used in the automotive industry to describe the longitudinal oscillation in a vehicle during its clutch system engagement. Past research has shown that judder can be explained using a behavior of slip speed and temperature captured by the clutch torque. This paper proposes and implements an innovative learning system for better characterization of the judder phenomenon. It is based on a multivariate data-driven analysis from torque signals. Our experimental results have been carried out using the following main resources: dry clutch system, passenger car, test bench, and six different organic facing materials. The multivariate statistical analysis implemented has allowed the development of a computationally efficient and highly accurate learning model to discriminate the torque signals from different facings, using few features and a regularized version of a standard linear classifier. Given this multivariate framework and calculating the correlation pairwisely to a known gold material, it has also been possible to predict judder problem in the vehicle based on a standard test bench in laboratory. We believe that the findings of this paper might reduce significantly the time of development and the cost of testing new friction materials for allowing judder-free performance on vehicles.
Autors: Ivan R. S. Gregori;Ivandro Sanches;Carlos E. Thomaz;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: May 2017, volume: 64, issue:5, pages: 4287 - 4295
Publisher: IEEE
 
» Co-Channel Interference and Background Noise in $kappa$ - $mu$ Fading Channels
Abstract:
In this letter, we derive novel analytical and closed form expressions for the outage probability, when the signal-of-interest (SoI) and the interferer experience – fading in the presence of Gaussian noise. Most importantly, these expressions hold true for independent and non-identically distributed – variates, without parameter constraints. We also find the asymptotic behaviour when the average signal to noise ratio of the SoI is significantly larger than that of the interferer. It is worth highlighting that our new solutions are very general owing to the flexibility of the – fading model.
Autors: Nidhi Bhargav;Carlos Rafael Nogueira da Silva;Young Jin Chun;Simon L. Cotton;Michel Daoud Yacoub;
Appeared in: IEEE Communications Letters
Publication date: May 2017, volume: 21, issue:5, pages: 1215 - 1218
Publisher: IEEE
 
» Co-Design Strategies for Energy-Efficient UWB and UHF Wireless Systems
Abstract:
This paper reviews the most recent methods, combining nonlinear harmonic-balance-based analysis with electromagnetic (EM) simulation, for optimizing, at the circuit level, modern radiative RF/microwave systems. In order to maximize the system efficiency, each subsystem must be designed layoutwise, accounting for the presence of the others, that is, accounting for its actual terminations, rather than the ideal ones (). In this way, the twofold goal of minimizing size and losses of the system is obtained by reducing intersystem matching networks. Indeed, terminations are complex, frequency-dispersive, and variable with the signal level, if active operations are concerned, and are responsible for performance degradation if not properly optimized. This approach is nowadays necessary, given the ever increased spread of pervasively distributed RF microsystems adopting miniaturized antennas, such as radio frequency identification (RFID) or wireless sensor networks, that must be low-cost, low-profile, low-power, and must simultaneously perform localization, identification, and sensing. For the design of a transmitter and a receiver connected with the respective antennas, suitable figures of merit are considered, encompassing radiation and nonlinear performance. Recent representative low-profile realizations, adopting ultra-wideband (UWB) excitations are used to highlight the benefit of the proposed nonlinear/EM approach for next generation energy autonomous microsystem, such as UWB-RFID tags.
Autors: Alessandra Costanzo;Diego Masotti;Marco Fantuzzi;Massimo Del Prete;
Appeared in: IEEE Transactions on Microwave Theory and Techniques
Publication date: May 2017, volume: 65, issue:5, pages: 1852 - 1863
Publisher: IEEE
 
» Co-Saliency Detection via a Self-Paced Multiple-Instance Learning Framework
Abstract:
As an interesting and emerging topic, co-saliency detection aims at simultaneously extracting common salient objects from a group of images. On one hand, traditional co-saliency detection approaches rely heavily on human knowledge for designing handcrafted metrics to possibly reflect the faithful properties of the co-salient regions. Such strategies, however, always suffer from poor generalization capability to flexibly adapt various scenarios in real applications. On the other hand, most current methods pursue cosaliency detection in unsupervised fashions. This, however, tends to weaken their performance in real complex scenarios because they are lack of robust learning mechanism to make full use of the weak labels of each image. To alleviate these two problems, this paper proposes a new SP-MIL framework for co-saliency detection, which integrates both multiple instance learning (MIL) and self-paced learning (SPL) into a unified learning framework. Specifically, for the first problem, we formulate the co-saliency detection problem as a MIL paradigm to learn the discriminative classifiers to detect the co-saliency object in the “instance-level”. The formulated MIL component facilitates our method capable of automatically producing the proper metrics to measure the intra-image contrast and the inter-image consistency for detecting co-saliency in a purely self-learning way. For the second problem, the embedded SPL paradigm is able to alleviate the data ambiguity under the weak supervision of co-saliency detection and guide a robust learning manner in complex scenarios. Experiments on benchmark datasets together with multiple extended computer vision applications demonstrate the superiority of the proposed framework beyond the state-of-the-arts.
Autors: Dingwen Zhang;Deyu Meng;Junwei Han;
Appeared in: IEEE Transactions on Pattern Analysis and Machine Intelligence
Publication date: May 2017, volume: 39, issue:5, pages: 865 - 878
Publisher: IEEE
 
» CO2 Concentration Using Adsorption and Nonthermal Plasma Desorption
Abstract:
Air-pollutant and greenhouse gas emissions typically have high gas flow rates and low concentrations (in ppm ∼ % levels, 1% = 10 000 ppm). The bulky equipment required for direct treatment of high-flow-rate low-concentration exhaust gases result in high-energy consumption and prohibitive operating costs. As such, the objective of this study is to convert high-flow-rate low-concentration exhaust gases into low-flow-rate high-concentration gases. This is achieved by desorbing the gas from an adsorbent by applying an atmospheric plasma inside a nonthermal plasma (NTP) reactor. This paper focuses on carbon dioxide (CO2) concentration (condensation) via this method. The adsorbent consists of spherical ∼2-mm-diameter molecular-sieve pellets of zeolite. Plasma desorption is performed by applying nanosecond high-voltage pulses (peak voltage ∼35 kV, pulse frequency = 140–350 Hz, and pulse width ∼600 ns) to the plasma reactor. A gas flow rate of 4 L/min is used and the concentrations of CO2, O2, H2O, and N2 gases are 2.75%, 18%, 1%, and the balance, respectively. The results reveal that CO2 can be desorbed effectively and more rapidly in a repeated adsorption and NTP desorption process than during the thermal process. Moreover, for the same electric power, the peak concentrations (typically 13%) are higher in the NTP desorption process than in the thermal process at equal electric power. These results indicate that the efficient NTP dissociation of CO2 to CO, which can be utilized in the production of combustion fuels, is possible.
Autors: Masaaki Okubo;Tomoyuki Kuroki;Hideaki Yamada;Keiichiro Yoshida;Takuya Kuwahara;
Appeared in: IEEE Transactions on Industry Applications
Publication date: May 2017, volume: 53, issue:3, pages: 2432 - 2439
Publisher: IEEE
 
» CO2 Laser Applications in Optical Fiber Components Fabrication and Treatment: A Review
Abstract:
CO2 laser has been widely used in material processing, manufacturing, and medical and military applications since its invention in 1964. Typically for optical fiber components fabrication and treatment, CO2 laser has been reported intensively in stress and birefringence modification, long period grating fabrication, thermal regeneration, optical device fabrication, surface polishing, photosensitivity enhancement, and so on. The reason behind this is due to the advantages of high absorption, fast thermal response, low contamination, dynamic control, and focused heating area owned by the CO2 laser treatment technique. In this paper, a wide variety of CO2 laser applications in optical fiber components fabrication and treatment are reviewed in terms of procedure and principle. The advantages of using CO2 laser and the supremacy of the optical fiber components fabricated or treated by CO2 laser are discussed as well.
Autors: Man-Hong Lai;Kok-Sing Lim;Dinusha Serandi Gunawardena;Yen-Sian Lee;Harith Ahmad;
Appeared in: IEEE Sensors Journal
Publication date: May 2017, volume: 17, issue:10, pages: 2961 - 2974
Publisher: IEEE
 
» Code Design for Flicker Mitigation in Visible Light Communications Using Finite State Machines
Abstract:
The IEEE 802.15.7 standard for visible light communication (VLC) includes the use of run-length-limited codes to mitigate modulation-induced flickering and the further use of coding to improve bit error rate performance. In this paper, we introduce algorithms to design codes using finite-state machines, which provide simultaneously a coding gain while also mitigating flicker. The codes have the additional advantage of being optimally soft-decision decodable using the Viterbi algorithm. To compare the flicker mitigation performance of different codes, we further introduce a mathematical measure of flicker based on the power spectrum of the transmitted signals. We discuss tradeoffs between flicker mitigation, code rate, and coding gain, design several codes, and compare their error rate and flicker mitigation performance to some codes in the VLC standard.
Autors: Carlos E. Mejia;Costas N. Georghiades;Mohamed M. Abdallah;Yazan H. Al-Badarneh;
Appeared in: IEEE Transactions on Communications
Publication date: May 2017, volume: 65, issue:5, pages: 2091 - 2100
Publisher: IEEE
 
» Code-Aided DOA Estimation From Turbo-Coded QAM Transmissions: Analytical CRLBs and Maximum Likelihood Estimator
Abstract:
In this paper, we address the problem of direction of arrival (DOA) estimation from turbo-coded square-QAM-modulated transmissions. We devise a new code-aware direction finding concept, derived from maximum likelihood (ML) theory, wherein the soft information provided by the soft-input soft-output decoder, in the form of log-likelihood ratios, is exploited to assist the estimation process. At each turbo iteration, the decoder output is used to refine the ML DOA estimate. The latter is in turn used to perform a more focused receiving beamforming thereby providing more reliable information-bearing sequences for the next turbo iteration. In order to benchmark the new estimator, we also derive the analytical expressions for the exact Cramer-Rao lower bounds (CRLBs) of code-aided (CA) DOA estimates. Simulation results will show that the new CA direction finding scheme lies between the two traditional schemes of completely non-data-aided and data-aided (DA) estimations. Huge performance improvements are achieved by embedding the direction finding and receive beamforming tasks into the turbo iteration loop. Moreover, the new CA DOA estimator reaches the new CA CRLBs over a wide range of practical SNRs thereby confirming its statistical efficiency. As expected intuitively, its performance further improves at higher coding rates and/or lower modulation orders.
Autors: Faouzi Bellili;Chaima Elguet;Souheib Ben Amor;Sofiène Affes;Alex Stéphenne;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: May 2017, volume: 16, issue:5, pages: 2850 - 2865
Publisher: IEEE
 
» Coded Caching for Multi-level Popularity and Access
Abstract:
To address the exponentially rising demand for wireless content, the use of caching is emerging as a potential solution. It has been recently established that joint design of content delivery and storage (coded caching) can significantly improve performance over conventional caching. Coded caching is well suited to emerging heterogeneous wireless architectures which consist of a dense deployment of local-coverage wireless access points (APs) with high data rates, along with sparsely-distributed, large-coverage macro-cell base stations (BS). This enables design of coded caching-and-delivery schemes that equip APs with storage, and place content in them in a way that creates coded-multicast opportunities for combining with macro-cell broadcast to satisfy users even with different demands. Such coded-caching schemes have been shown to be order-optimal with respect to the BS transmission rate, for a system with single-level content, i.e., one where all content is uniformly popular. In this paper, we consider a system with non-uniform popularity content which is divided into multiple levels, based on varying degrees of popularity. The main contribution of this paper is the derivation of an order-optimal scheme which judiciously shares cache memory among files with different popularities. To show order-optimality we derive new information-theoretic lower bounds, which use a sliding-window entropy inequality, effectively creating a non-cut-set bound. We also extend the ideas to when users can access multiple caches along with the broadcast. Finally, we consider two extreme cases of user distribution across caches for the multi-level popularity model: a single user per cache (single-user setup) versus a large number of users per cache (multi-user setup), and demonstrate a dichotomy in the order-optimal strategies for these two extreme cases.
Autors: Jad Hachem;Nikhil Karamchandani;Suhas N. Diggavi;
Appeared in: IEEE Transactions on Information Theory
Publication date: May 2017, volume: 63, issue:5, pages: 3108 - 3141
Publisher: IEEE
 
» Coding for Classical-Quantum Channels With Rate Limited Side Information at the Encoder: Information-Spectrum Approach
Abstract:
We study the hybrid classical-quantum version of the channel coding problem for the famous Gel’fand–Pinsker channel. In the classical setting for this channel the conditional distribution of the channel output given the channel input is a function of a random parameter called the channel state. We study this problem when a rate limited version of the channel state is available at the encoder for the classical-quantum Gel’fand–Pinsker channel. We establish the capacity region for this problem in the information-spectrum setting. The capacity region is quantified in terms of spectral-sup classical mutual information rate and spectral-inf quantum mutual information rate.
Autors: Naqueeb Ahmad Warsi;Justin P. Coon;
Appeared in: IEEE Transactions on Information Theory
Publication date: May 2017, volume: 63, issue:5, pages: 3322 - 3331
Publisher: IEEE
 
» Coil-Shaped Electrodes to Reduce the Current Variation of Drop-Casted OTFTs
Abstract:
Coil-shaped structures are proposed to reduce the impact of variable grain alignment on the drive current of the polycrystalline organic thin-film transi-stors (OTFT). Top-gate, bottom-contact polycrystalline OTFT is fabricated with the drop-casted semiconducting layer to verify the proposed structures. The relative standard deviation (RSD) defined as the ratio of standard deviation, and the average of drive current is used for comparing variations between different structures. Coil-shaped transistors have a significantly lower (22%) RSD, compared with the conventional structures (61%). Finally, we present a technique for designing symmetric coil-shaped OTFTs of any arbitrary W/L ratio (>1) with reduced current variation.
Autors: H. M. Dipu Kabir;Zubair Ahmed;Lining Zhang;Mansun Chan;
Appeared in: IEEE Electron Device Letters
Publication date: May 2017, volume: 38, issue:5, pages: 645 - 648
Publisher: IEEE
 
» Color Image-Guided Boundary-Inconsistent Region Refinement for Stereo Matching
Abstract:
Cost computation, cost aggregation, disparity optimization, and disparity refinement are the four main steps for stereo matching. While the first three steps have been widely investigated, few efforts have been taken on disparity refinement. In this paper, we propose a color image-guided disparity refinement method to further remove the boundary-inconsistent regions on disparity map. First, the origins of boundary-inconsistent regions are analyzed. Then, these regions are detected with the proposed hybrid-superpixel-based strategy. Finally, the detected boundary-inconsistent regions are refined by a modified weighted median filtering method. Experimental results on various stereo matching conditions validate the effectiveness of the proposed method. Furthermore, depth maps obtained by active depth acquisition devices like Kinect can also be well refined with our proposed method.
Autors: Jianbo Jiao;Ronggang Wang;Wenmin Wang;Dagang Li;Wen Gao;
Appeared in: IEEE Transactions on Circuits and Systems for Video Technology
Publication date: May 2017, volume: 27, issue:5, pages: 1155 - 1159
Publisher: IEEE
 
» ColorSketch: A Drawing Assistant for Generating Color Sketches from Photos
Abstract:
A color sketch creates a vivid depiction of a scene using sparse pencil strokes and casual colored brush strokes. The interactive drawing system ColorSketch can help novice users generate color sketches from photos. To preserve artistic freedom and expressiveness, the proposed system gives users full control over pencil strokes, while automatically augmenting pencil sketches using color mapping, brush stroke rendering, and blank area creation. Experimental and user study results demonstrate that users, especially novices, can create better color sketches with our system than when using traditional manual tools.
Autors: Guanbin Li;Sai Bi;Jue Wang;Yingqing Xu;Yizhou Yu;
Appeared in: IEEE Computer Graphics and Applications
Publication date: May 2017, volume: 38, issue:3, pages: 70 - 81
Publisher: IEEE
 
» Combined Speed and Direct Thrust Force Control of Linear Permanent-Magnet Synchronous Motors With Sensorless Speed Estimation Using a Sliding-Mode Control With Integral Action
Abstract:
A sliding-mode-based control scheme with integral action for combined speed and direct thrust force control of a linear permanent-magnet synchronous motor is proposed. A nonlinear state-space model for the combined dynamics of speed and thrust force as system states is utilized for the synthesis of the sliding-mode control law. Direct integral action is also included in the control law to eliminate the steady-state error in the speed tracking. The sensorless speed estimation is performed by using an adaptive flux observer with a modified dual boundary layer sliding-mode component. Lyapunov stability analysis to prove the global asymptotic stabilities of both the controller and observer is provided. The effectiveness of the proposed method is validated experimentally and demonstrates excellent transient and steady-state speed control performance.
Autors: Muhammad Ali Masood Cheema;John Edward Fletcher;Mohammad Farshadnia;Dan Xiao;Muhammad Faz Rahman;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: May 2017, volume: 64, issue:5, pages: 3489 - 3501
Publisher: IEEE
 
» Comments on “An Analytical Design Method for a Novel Dual-Band Unequal Coupler With Four Arbitrary Terminated Resistances”
Abstract:
IN the above paper [1], the authors proposed a dual-band unequal power division branch line coupler(BLC) with four arbitrary terminated resistance using dual-band impedance matching network (IMN) and BLC with complex port impedance. However the authors have not considered the transmission phase of the IMNs [2] and the BLC, which leads to non-quadrature phase difference (6 S21􀀀6 S31 6= 90) at the output ports when the termination resistances are unequal.
Autors: Rakesh Sinha;Arijit De;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: May 2017, volume: 64, issue:5, pages: 4068 - 4069
Publisher: IEEE
 
» Comments on “Simultaneous Reduction of Petri Nets and Linear Constraints for Efficient Supervisor Synthesis”
Abstract:
The above paper [1] proposes a method to reduce simultaneously a Petri net model and the linear constraints. The reduced result preserves the control specification and the liveness. This note shows via some simple counterexamples that some results claimed in the above paper are incorrect, and then presents the corresponding corrections for two of the results.
Autors: Ning Ran;Shouguang Wang;Hongye Su;
Appeared in: IEEE Transactions on Automatic Control
Publication date: May 2017, volume: 62, issue:5, pages: 2603 - 2606
Publisher: IEEE
 
» Communications and Signals Design for Wireless Power Transmission
Abstract:
Radiative wireless power transfer (WPT) is a promising technology to provide cost-effective and real-time power supplies to wireless devices. Although radiative WPT shares many similar characteristics with the extensively studied wireless information transfer or communication, they also differ significantly in terms of design objectives, transmitter/receiver architectures and hardware constraints, and so on. In this paper, we first give an overview on the various WPT technologies, the historical development of the radiative WPT technology and the main challenges in designing contemporary radiative WPT systems. Then, we focus on the state-of-the-art communication and signal processing techniques that can be applied to tackle these challenges. Topics discussed include energy harvester modeling, energy beamforming for WPT, channel acquisition, power region characterization in multi-user WPT, waveform design with linear and non-linear energy receiver model, safety and health issues of WPT, massive multiple-input multiple-output and millimeter wave enabled WPT, wireless charging control, and wireless power and communication systems co-design. We also point out directions that are promising for future research.
Autors: Yong Zeng;Bruno Clerckx;Rui Zhang;
Appeared in: IEEE Transactions on Communications
Publication date: May 2017, volume: 65, issue:5, pages: 2264 - 2290
Publisher: IEEE
 
» Compact 35–70 GHz SPDT Switch With High Isolation for High Power Application
Abstract:
This letter proposes a broadband high isolation and high power compact single pole double throw (SPDT) switch. In contrast to the traditional structure of grounded source pad, the source pad of the shunt-stacked FET is absorbed into the transmission line, and the drain of the shunt-stacked FET is grounded to a via-hole. This structure helps to extend the operation bandwidth and reduce the chip size. The proposed SPDT switch is composed of six shunt-stacked FET units on each branch with this novel structure. Stacked FETs technique increases the voltage handling by placing two FETs in series. It has been fabricated using a commercial GaAs pseudomorphic high-electron-mobility transistor (PHEMT) process. The chip size is mm2. The switch operates at the frequency range of 35–70 GHz with less than 3 dB insertion loss and more than 40-dB isolation. The switch demonstrates a 1 dB insertion loss compression with a 20.2 dBm input power at 31 GHz. The isolation is larger than 30 dB from 10 to 95 GHz. To the best of the authors’ knowledge, this broadband isolation performance is among the best of the reported SPDT switches.
Autors: Li Zhao;Wen-Feng Liang;Jian-Yi Zhou;Xin Jiang;
Appeared in: IEEE Microwave and Wireless Components Letters
Publication date: May 2017, volume: 27, issue:5, pages: 485 - 487
Publisher: IEEE
 
» Compact Folded Dipole With Embedded Matching Loop for Universal Tag Applications
Abstract:
A coin-shaped folded dipole is proposed for designing a UHF tag that can be placed in free space and on metal. The proposed tag antenna is compact ( and low in profile (1.6 mm). It is composed of a matching loop, which is encircled by two patch-shaped radiating arms, forming an embedded structure that has high compactness. Slots are etched in the radiators for fine-tuning the resonant frequency. An equivalent circuit has also been obtained for analyzing the impedance characteristics of the tag antenna across the frequency range, and it is found that the radiating element itself is capacitive and inclusion of the matching loop is essential for making the tag antenna inductive for achieving good matching with the chip. Simulation and experiment have been conducted to study the charateristics of the proposed tag antenna. When tested in free space with an Effective Isotropic Radiated Power (EIRP) input power of 3.28 W, the tag antenna is able to reach a maximum read range of 5.2 m, but it reduces to 1.8 m when placed on metal. Also, the resonant frequency of the proposed tag antenna is found to be stable and not affected much by its backing object.
Autors: Fwee-Leong Bong;Eng-Hock Lim;Fook-Loong Lo;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: May 2017, volume: 65, issue:5, pages: 2173 - 2181
Publisher: IEEE
 
» Compact Multimode Monopole Antenna for Metal-Rimmed Mobile Phones
Abstract:
A compact multimode monopole antenna for hepta-band metal-rimmed smartphones is proposed. The metal bezel is kept unbroken and no lumped element is needed. To cover the low band, the bezel mode is excited by a capacitive coupling vertical plate, and a bandwidth enhancement technique is introduced for this mode. For the high band, printed multiple branches on both sides of substrate are well designed to obtain multiple modes to cover a wide band. With the proposed structure, the frequency bands can be widened by tuning and optimization. The new-type monopole occupies an area of mm on a mm system board, which has a narrow ground clearance and a low profile. A prototype is fabricated and measured to validate the proposed design. Measured results show that the proposed antenna has two impedance bands with less than −6 dB, i.e., 23% for the low band (0.76–0.96 GHz) and 57% for the high band (1.51–2.72 GHz). The proposed monopole antenna is capable of covering the GSM/DCS/PCS/UMTS and LTE2300/2500 bands for modern metal-rimmed mobile phone applications.
Autors: Yaohui Yang;Zhiqin Zhao;Wei Yang;Zaiping Nie;Qing-Huo Liu;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: May 2017, volume: 65, issue:5, pages: 2297 - 2304
Publisher: IEEE
 
» Compact Neuromorphic System With Four-Terminal Si-Based Synaptic Devices for Spiking Neural Networks
Abstract:
In this paper, we propose a compact neuromorphic system that can work with four-terminal Si-based synaptic devices for spiking neural networks. The system consists of Si-based floating-body synaptic transistors and integrate-and-fire neuron circuit. The synaptic device can change its weight using floating-body effect and charge injection into the floating gate. The neuron circuit integrates signals from the synaptic devices through current mirrors and generates an action-potential when the integrated signal value exceeds a threshold value. The generated action potential that is transmitted to postsynaptic neurons is simultaneously returned to the back gate of the synaptic device for the change of weight based on spike-timing-dependent-plasticity. As the four-terminal synaptic device can transmit preneuron signals and change its weight at the same time, we can constitute the compact neuromorphic system without additional switches or logic operation and emulate the operation of neuron with a minimum number of devices and power dissipation (~3 pJ).
Autors: Jungjin Park;Min-Woo Kwon;Hyungjin Kim;Sungmin Hwang;Jeong-Jun Lee;Byung-Gook Park;
Appeared in: IEEE Transactions on Electron Devices
Publication date: May 2017, volume: 64, issue:5, pages: 2438 - 2444
Publisher: IEEE
 
» Compact UHF Three-Element Sequential Rotation Array Antenna for Satcom Applications
Abstract:
This paper proposes a miniaturized UHF antenna with three sequentially rotated elements operating at 433 MHz for Satcom applications. Like most of its former counterparts, the antenna consists of a main body with three radiation elements driven by a feeding network. To evaluate the matching characteristics of the main body, a united reflection coefficient for the three elements, taking into consideration the coupling between them, is derived. The main body is formed by three sequentially rotationally arranged bent planar inverted-F antenna elements, which helps dramatically reduce the size of the antenna. To drive the main body, a new compact feeding network based on spiral-shaped Wilkinson power divider is also developed, achieving three-way power splitting and 120° phase shifting. It has the merits of compact planar structure, equal power splitting, and high isolation between output ports. In this way, a sequential rotation array antenna with compact size (Ø), low cost, easy fabrication, and good performance is realized. A prototype is fabricated and measured, and the results prove the good performance of the proposed design.
Autors: Shaowei Liao;Quan Xue;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: May 2017, volume: 65, issue:5, pages: 2328 - 2338
Publisher: IEEE
 
» Comparative Analysis of the Doubly Fed Induction Generator (DFIG) Under Balanced Voltage Sag Using a Deadbeat Controller
Abstract:
This paper shows a Deadbeat controller for a wind generator during a balanced voltage sag condition. The control is made with a Stator Field Oriented Control technique using the DSOGI-QSG applied on the estimation of positive sequence of stator voltage vector and the stator current vector. The control strategy used is fully explained, and then it is tested using Matlab/Simulink, considering two scenarios: for the first one, the generator must be forced to generate reactive power and maintain the active power in zero, during voltage sag condition according with the new network requirements. For the second test, the generator must maintain rotor currents within safe levels to prevent damages for the windings during voltage sag. Simulation results and conclusions about controller perfomance during the voltage sag condition are presented.
Autors: Carlos Mario Rocha Osorio;Juan Sebastian Solis Chaves;Andre Luiz de Lacerda Ferreira Murari;Alfeu Joaozinho Sguarezi Filho;
Appeared in: IEEE Latin America Transactions
Publication date: May 2017, volume: 15, issue:5, pages: 869 - 876
Publisher: IEEE
 
» Comparing Performances of Crop Height Inversion Schemes From Multifrequency Pol-InSAR Data
Abstract:
Polarimetric synthetic aperture radar (SAR) interferometry has shown great potential to estimate the height of crops and forests by inverting simple scattering models of the canopy and the underlying soil. The random-volume-over-ground (RVoG) model assumes that the scatterers within the canopy (e.g., stalks and leaves) are not aligned along a preferred direction. If these scatterers are characterized by a correlation of orientations, then the scene is better described by the oriented-volume-over-ground (OVoG) model. This paper investigates the plausibility of the “random volume” and “oriented volume” assumptions, as well as the robustness of single- and dual-baseline inversion schemes in relation to agricultural crop height estimation. To this end, we implemented different single- and dual-baseline techniques for the inversion of the RVoG and OVoG models, and we evaluated their height retrieval performances with the help of simulated observations and experimental F-SAR measurements in L-, C-, and X-Bands. The inversion results revealed a positive relationship between the bias of the estimated height and the differential extinction when the RVoG inversion scheme is applied. By contrast, no such dependence was observed for the OVoG inversion, whose height estimates are on average consistent with the actual values (i.e., median bias below 10% in magnitude). Despite the observed superiority of dual-baseline approaches, the study also pointed out the feasibility of crop height estimation using single-baseline RVoG inversion schemes, provided the appropriate a priori constraints (e.g., on the extinction coefficient) and crop-specific configuration parameters (e.g., C-Band for maize, and C- and X-Bands for wheat).
Autors: Manuele Pichierri;Irena Hajnsek;
Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Publication date: May 2017, volume: 10, issue:5, pages: 1727 - 1741
Publisher: IEEE
 
» Comparison Between Output CM Chokes for SiC Drive Operating at 20- and 200-kHz Switching Frequencies
Abstract:
The adoption of silicon carbide (SiC) MOSFETs in variable speed drives (VSDs) makes it possible to increase the inverter switching frequency up to several hundred kilohertz without incurring excessive inverter loss. As a result, the harmonic currents and related losses in the machine can be significantly reduced, and the dynamic performance of motor will also be improved. However, the high switching frequency will increase the common mode (CM) electromagnetic interference (EMI) emission of the drive system presenting new challenges on CM choke design. In the literature, chokes designed for VSDs operating above 100 kHz are rarely found. Hence, this paper presents a case study on the output CM chokes for a SiC-based VSD switching at 20 and 200 kHz. A comprehensive comparison is made between the chokes for two switching frequencies regarding design, sizing, and performance, through both calculation and experiments. The results show that the CM choke designed for 200 kHz switching frequency is significantly larger and heavier than the 20 kHz choke, due to the higher inductance value required to meet the EMI limit and the lower permeability of the core material. Meanwhile, the 200 kHz choke is also less effective in noise attenuation as a result of the larger winding capacitance compared with the 20 kHz choke.
Autors: Di Han;Casey T. Morris;Woongkul Lee;Bulent Sarlioglu;
Appeared in: IEEE Transactions on Industry Applications
Publication date: May 2017, volume: 53, issue:3, pages: 2178 - 2188
Publisher: IEEE
 
» Compartmental and Data-Based Modeling of Cerebral Hemodynamics: Nonlinear Analysis
Abstract:
Objective: As an extension to our study comparing a putative compartmental and data-based model of linear dynamic cerebral autoregulation (CA) and CO2-vasomotor reactivity (VR), we study the CA–VR process in a nonlinear context. Methods: We use the concept of principal dynamic modes (PDM) in order to obtain a compact and more easily interpretable input–output model. This in silico study permits the use of input data with a dynamic range large enough to simulate the classic homeostatic CA and VR curves using a putative structural model of the regulatory control of the cerebral circulation. The PDM model obtained using theoretical and experimental data are compared. Results: It was found that the PDM model was able to reflect accurately both the simulated static CA and VR curves in the associated nonlinear functions (ANFs). Similar to experimental observations, the PDM model essentially separates the pressure-flow relationship into a linear component with fast dynamics and nonlinear components with slow dynamics. In addition, we found good qualitative agreement between the PDMs representing the dynamic theoretical and experimental CO2-flow relationship. Conclusion: Under the modeling assumption and in light of other experimental findings, we hypothesize that PDMs obtained from experimental data correspond with passive fluid dynamical and active regulatory mechanisms. Significance: Both hypothesis-based and data-based modeling approaches can be combined to offer some insight into the physiological basis of PDM model obtained from human experimental data. The PDM modeling approach potentially offers a practical way to quantify the status of specific regulatory mechanisms in the CA–VR process.
Autors: Brandon Christian Henley;Dae C. Shin;Rong Zhang;Vasilis Z. Marmarelis;
Appeared in: IEEE Transactions on Biomedical Engineering
Publication date: May 2017, volume: 64, issue:5, pages: 1078 - 1088
Publisher: IEEE
 
» Compensating XPM Using a Low-Bandwidth Phase Modulator
Abstract:
We experimentally demonstrate, for the first time, cross-phase modulation (XPM) compensation using an optical phase modulator and low-bandwidth electronics. We first show that our nonlinearity compensator suppresses the XPM distortion from a 10-Gb/s ON-OFF keyed (OOK) channel on a continuous-wave (CW) probe signal. We then replace the CW tone with a 28-Gbaud quadrature phase-shift keyed (QPSK) signal and show that the OOK power can be doubled when XPM compensation is used. This demonstrates proof-of-concept for XPM compensation using phase modulators placed along a fiber link.
Autors: Benjamin Foo;Bill Corcoran;Arthur Lowery;
Appeared in: IEEE Photonics Technology Letters
Publication date: May 2017, volume: 29, issue:9, pages: 699 - 702
Publisher: IEEE
 
» Compensation of Transmitter I/Q Imbalance in Millimeter-Wave SC-FDE Systems
Abstract:
Due to imperfect analog processing, millimeter-wave communication is confronted with severe radio frequency impairments, such as in-phase/quadrature (IQ) imbalance. The presence of I/Q imbalance introduces image interference to the desired signal and can significantly degrade the performance if not compensated. In this paper, we propose a novel training-based compensation method for transmitter (TX) I/Q imbalance in millimeter-wave single carrier with frequency domain equalization (SC-FDE) systems. The novelty of the proposed method is that it can obtain the separate estimates of the TX I/Q imbalance and multipath channel. With the obtained estimates, we can easily conduct the FDE and compensate for the TX I/Q imbalance by simple operations. Simulations show that the proposed method can accurately estimate the TX I/Q imbalance and multipath channel and, thus, can achieve almost the same performance as the ideal case free of TX I/Q imbalance.
Autors: Xiantao Cheng;Zengqiang Luo;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: May 2017, volume: 66, issue:5, pages: 4472 - 4476
Publisher: IEEE
 
» Completion Time in Two-User Channels: An Information-Theoretic Perspective
Abstract:
Consider a multi-user channel, where each user has a large but non-replenishable bit pool to transmit. Completion time refers to the number of channel uses spent by each user to complete its transmission. In this paper, an information-theoretic formulation of completion time is based on the concept of constrained rates, which are defined over possibly different number of channel uses. Analogous to the capacity region, the completion time region characterizes all possible trade-offs among users’ completion times. For a two-user multi-access channel, it is shown that the completion time region is achieved by operating the channel in two independent phases: a multi-access phase when both users are transmitting, and a point-to-point phase when one user has finished and the other is still transmitting. Using a similar two-phase approach, the completion time regions (or inner and outer bounds) are established for a two-user Gaussian broadcast channel and a two-user Gaussian interference channel. It is observed that although consisting of two convex subregions, the completion time region may not be convex in general. Finally, optimization problems of minimizing the weighted sum completion time for a Gaussian multi-access channel and a Gaussian broadcast channel are solved, demonstrating the utility of the completion time approach.
Autors: Yuanpeng Liu;Elza Erkip;
Appeared in: IEEE Transactions on Information Theory
Publication date: May 2017, volume: 63, issue:5, pages: 3209 - 3223
Publisher: IEEE
 
» Complex-Network-Inspired Design of Traffic Generation Patterns in Communication Networks
Abstract:
In this brief, we consider a generic type of communication network consisting of two kinds of nodes, i.e., hosts and routers, and only the hosts can generate and receive packets. In this kind of network, the traffic performance is closely related to the traffic generation pattern, which strongly depends on the hosts' locations. We employ a simulated annealing algorithm to find a near-optimal configuration of the hosts, which effectively balances the traffic loads and improves the overall traffic performance. Our study suggests that the traffic generation pattern is an important factor for communication network design.
Autors: Jiajing Wu;Yongxiang Xia;
Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs
Publication date: May 2017, volume: 64, issue:5, pages: 590 - 594
Publisher: IEEE
 
» Comprehensive Peak-Shaving Solutions for Port Cranes
Abstract:
This paper discusses the reduction of the maximum power demand of shore-to-ship cranes from the supply power system by the implementation of ultracapacitors and flywheels that locally store up and compensate a rate of the power demand, and by a power optimization tool that shaves the maximum peak of a cranes’ group, coordinating their duty cycles. These reductions can lead to reduced electrical infrastructure system resulting installation and operating expenses for operating shore-ship cranes. The concept presented in the paper is encouraging port facilities developments and modernization to make sustainable microgrids based upon four (l) pillars using leveled, less, local, and load (lele-lolo).
Autors: Giuseppe Parise;Luigi Parise;Andrea Malerba;Francesco Maria Pepe;Alberto Honorati;Peniamin Ben Chavdarian;
Appeared in: IEEE Transactions on Industry Applications
Publication date: May 2017, volume: 53, issue:3, pages: 1799 - 1806
Publisher: IEEE
 
» Compressed FEC Codes With Spatial-Coupling
Abstract:
An error floor problem is observed for a spatially coupled sparse-regression (SCSR) code with limited sparsity in low-to-medium rates. This letter presents a scheme that also involves spatial-coupling and compressed-sensing (SCCS) similar to SCSR. We replace position modulation in SCSR by a general concatenated forward error control code. We introduce a chaining principle that improves the error floor behavior of the underlying code. We show that SCCS based on chained Hadamard codes can offer significantly improved performance.
Autors: Chulong Liang;Junjie Ma;Li Ping;
Appeared in: IEEE Communications Letters
Publication date: May 2017, volume: 21, issue:5, pages: 987 - 990
Publisher: IEEE
 
» Computation Time Analysis of the Magnetic Gear Analytical Model
Abstract:
This paper focuses on the computation time and precision of a linear 2-D magnetic gear analytical model. Two main models of magnetic gears are studied: 1) the first with an infinite relative permeability of yokes and 2) the second with a finite relative permeability of yokes. These models are based on the subdomain resolution of Laplace and Poisson equations. To accurately compute the magnetic field distribution, it is necessary to take into account certain harmonics of the various rings and other system harmonics due to modulation. Global system harmonics, which increase the value of computation time, must also be taken into account. If the magnetic gear has a high pole number, then computation time increases even more and no longer allows for system optimization. This paper proposes to compute magnetic field distribution using different harmonic selection methods in order to significantly reduce the computation time for the magnetic torque without any loss of accuracy.
Autors: Melaine Desvaux;Benjamin Traullé;Roman Le Goff Latimier;Stéphane Sire;Bernard Multon;Hamid Ben Ahmed;
Appeared in: IEEE Transactions on Magnetics
Publication date: May 2017, volume: 53, issue:5, pages: 1 - 9
Publisher: IEEE
 
» Computational Depth Sensing : Toward high-performance commodity depth cameras
Abstract:
Depth information plays an important role in a variety of applications, including manufacturing, medical imaging, computer vision, graphics, and virtual/augmented reality (VR/AR). Depth sensing has thus attracted sustained attention from both academia and industry communities for decades. Mainstream depth cameras can be divided into three categories: stereo, time of flight (ToF), and structured light. Stereo cameras require no active illumination and can be used outdoors, but they are fragile for homogeneous surfaces. Recently, off-the-shelf light field cameras have demonstrated improved depth estimation capability with a multiview stereo configuration. ToF cameras operate at a high frame rate and fit time-critical scenarios well, but they are susceptible to noise and limited to low resolution [3]. Structured light cameras can produce high-resolution, high-accuracy depth, provided that a number of patterns are sequentially used. Due to its promising and reliable performance, the structured light approach has been widely adopted for three-dimensional (3-D) scanning purposes. However, achieving real-time depth with structured light either requires highspeed (and thus expensive) hardware or sacrifices depth resolution and accuracy by using a single pattern instead.
Autors: Zhiwei Xiong;Yueyi Zhang;Feng Wu;Wenjun Zeng;
Appeared in: IEEE Signal Processing Magazine
Publication date: May 2017, volume: 34, issue:3, pages: 55 - 68
Publisher: IEEE
 
» Computational Design and Fabrication
Abstract:
Computer graphics research is increasingly interested in the high-level analysis and processing of geometric objects. By acquiring a structural or functional understanding of 3D shapes, researchers are able to tackle mid- to high-level design problems for which machine computations can replace or at least relieve human efforts. In parallel, with the rapid advances in 3D printing technologies, many design solutions explored by researchers and practitioners are focusing on the needs and constraints arising from physical fabrication. The contributions in this special issue are cross-disciplinary, connecting physical fabrication with design and processing tasks in new domains including circuit design, geospatial visualization, and 3D scanning, leading to never-before-seen 3D printing applications.
Autors: Bedrich Benes;David J. Kasik;Wilmot Li;Hao Zhang;
Appeared in: IEEE Computer Graphics and Applications
Publication date: May 2017, volume: 38, issue:3, pages: 32 - 33
Publisher: IEEE
 
» Computationally Efficient Adjustment of FACTS Set Points in DC Optimal Power Flow With Shift Factor Structure
Abstract:
Enhanced utilization of the existing transmission network is a cheaper and paramount alternative to building new transmission lines. Flexible ac transmission system (FACTS) devices are advanced technologies that offer transfer capability improvements via power flow control. Although many FACTS devices exist in power systems, their set points are not frequently changed for power flow control purposes, which is mainly due to the computational complexity of incorporating FACTS flexibility within the market problem. This paper proposes a computationally efficient method for adjustment of variable impedance-based FACTS set points, which is also compatible with existing market solvers. Thus, the method can be employed by the existing solvers with minimal modification efforts. This paper models FACTS reactance control as injections to keep the initial shift factors unchanged. Next, the paper formulates a dc optimal power flow that co-optimizes FACTS set points alongside generation dispatch. The resulting problem, which is in a nonlinear program, is then reformulated to a mixed-integer linear program. Finally, an engineering insight is leveraged to further reduce the computational complexity to a linear program. Simulation studies on IEEE 118-bus and Polish 2383-bus test cases show that the method is extremely effective in finding quality solutions and being very fast.
Autors: Mostafa Sahraei-Ardakani;Kory W. Hedman;
Appeared in: IEEE Transactions on Power Systems
Publication date: May 2017, volume: 32, issue:3, pages: 1733 - 1740
Publisher: IEEE
 
» Computerized Dungeons and Randomly Generated Worlds: From Rogue to Minecraft
Abstract:
Replayability is a major factor in the long-term enjoyment of a video game. Many games can be engrossing on the first playthrough, but those with fixed solutions and singular paths through multiple levels of skill can quickly lose their appeal after the first win. One approach to replayability is randomly generated content, which ensures a different playthrough each time. While numerous role-playing games simulate dice rolls, procedural generation in games used predefined seed values in combination with pseudorandom number generators to create entire levels and item sets. Rogue is one of the earliest examples of games to focus core gameplay elements around randomly generated levels and items, and its popularity within the UNIX community led to a group of dedicated fans making their own improvements on the game and sharing their modifications online. These derivatives of Rogue, known as “roguelikes,” have more than a 30-year history of development, and many are still maintained to this day.
Autors: Nathan Brewer;
Appeared in: Proceedings of the IEEE
Publication date: May 2017, volume: 105, issue:5, pages: 970 - 977
Publisher: IEEE
 
» Concentrated Winding IPM Synchronous Motor Design for Wide Field Weakening Applications
Abstract:
In order to understand the impact that certain design changes may have on the performance over a wide speed range, a series of 12-slot 8-pole concentrated winding interior permanent magnet synchronous motors (IPMSMs) are analyzed. Fundamental theory of operation is used to describe the desirable characteristics in terms of the lumped parameters, and finite element analysis is carried out to show how these characteristics may be realized through the motor geometry changes. The motor geometry changes aim to create an IPMSM design with high d-axis inductance for the wide speed range operation, low harmonic content in the back electromotive force waveform, and low cogging torque. A prototype is constructed and test results are presented for verification.
Autors: Mohammad Sedigh Toulabi;John Salmon;Andrew M. Knight;
Appeared in: IEEE Transactions on Industry Applications
Publication date: May 2017, volume: 53, issue:3, pages: 1892 - 1900
Publisher: IEEE
 
» Condensable Supersonic Jet Facility for Analyses of Transient Low-Temperature Gas Kinetics and Plasma Chemistry of Hydrocarbons
Abstract:
LEMPUS-2 facility is designed and built to study processes of cluster formation and plasma-chemical reactions that include atoms, molecules, and clusters, in supersonic jets. The facility is equipped with modern diagnostics tools and molecular-beam, electron-beam, mass-spectrometer, spectrometer, and laser systems for testing and fine-tuning technological processes in a laboratory environment. One of the key advantages of the discussed facility is that in a single system and a single experiment, it combines the tools for the activation of transient and steady-state supersonic flow with self-sustaining or nonself-sustaining discharge, and flow analysis using electron-beam spectroscopy and molecular-beam mass spectroscopy. Dry roughing and high-vacuum pumps enable accurate diagnostics of chemically reacting processes in virtually any gas mixture, including hydrocarbons. A pulsed flow regime controlled by developed in-house fast valves provides an efficient way to examine quasi-stationary flows at fairly high flow rates, with significant material and energy savings. The facility serves a number of purposes, from cluster-surface interaction studies with thin film and surface structure formation, to high-pressure jet expansions that emulate spacecraft nozzles at high altitudes, to technological process development, primarily focused on hydrocarbons. Details of key applications of the facility are presented that include the gas dynamics of cluster jets, the formation of heterogeneous clusters, the study of plasma-chemistry of hydrocarbons, and the thin film deposition.
Autors: A. E. Zarvin;V. V. Kalyada;V. Zh. Madirbaev;N. G. Korobeishchikov;M. D. Khodakov;A. S. Yaskin;V. E. Khudozhitkov;S. F. Gimelshein;
Appeared in: IEEE Transactions on Plasma Science
Publication date: May 2017, volume: 45, issue:5, pages: 819 - 827
Publisher: IEEE
 
» Conference Report on 2016 IEEE Symposium Series on Computational Intelligence (IEEE SSCI 2016) [Conference Reports]
Abstract:
Presents information on the IEEE SSCI 2016 Conference.
Autors: Yaochu Jin;Stefanos Kollias;
Appeared in: IEEE Computational Intelligence Magazine
Publication date: May 2017, volume: 12, issue:2, pages: 18 - 19
Publisher: IEEE
 
» Confidence Estimates in Simulation of Phase Noise or Spectral Density
Abstract:
In this paper, we apply the method of discrete simulation of power-law noise, developed by Timmer and König, Ashby, and Ashby and Patla, to the problem of simulating phase noise for a combination of power-law noises. We derive analytic expressions for the probability of observing a value of phase noise or of any of the one-sided spectral densities , or , for arbitrary superpositions of power-law noise.
Autors: Neil Ashby;
Appeared in: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control
Publication date: May 2017, volume: 64, issue:5, pages: 872 - 878
Publisher: IEEE
 
» Connecting a City by Wireless Backhaul: 3D Spatial Channel Characterization and Modeling Perspectives
Abstract:
The backhaul forwards aggregated traffic from massive users, machines, and sensors to the core network, and is the key infrastructure to facilitate a smart city. The beamforming and spatial multiplexing technologies enable the wireless multipoint-to-point backhaul to connect dense small cell eNodeBs (eNBs) and macrocell eNBs. Because the spatial characteristics of the backhaul channels, such as the angular power spectra and spreads, determine the interference and capacity performance of the backhaul links, accurate 3D channel modeling is vital for the evaluation and comparison of candidate proposals. In this article, the concepts and methodology of spatial channel modeling are first introduced, and the state-of-the-art models developed by the standardization bodies in recent years are surveyed. Then we present a field measurement campaign on the 3D backhaul channels in an urban street, including the channel sounder implementation, field measurement, multipath parameter estimation, and propagation modeling. The Rx of the sounder (emulating a donor eNB) was installed on the rooftop of a five-story building, and the Tx was located along a street and at different altitudes to emulate a relay eNB. The channel angular power spectra in the elevation and azimuth domains were measured, and the impact by the relay�s distance and altitude on the angular spreads was evaluated. In addition, a Laplace model is proposed for the power spectra in both domains. This article not only explains the methodology and implementation of the spatial channel measurement, but also reveals the urban wireless backhaul channel characteristics which are useful for the design and deployment of wireless backhaul for a smart city.
Autors: Ruonan Zhang;Xiaohong Jiang;Tarik Taleb;Bin Li;Heng Qin;Zhimeng Zhong;Xiaomei Zhang;
Appeared in: IEEE Communications Magazine
Publication date: May 2017, volume: 55, issue:5, pages: 62 - 69
Publisher: IEEE
 
» Considerations for Dependability of the Motor Protection on Current Transformers Performance in VFD Applications
Abstract:
When generators or motors are started via variable frequency drive (VFD), initial frequency is very low, on the order of few hertz, and can be low for a considerable amount of time or even permanently. It is not well recognized in the industry about the consequences of low frequency on current transformers (CTs) performance and how this affects the protection performance as well. First, CTs are designed to operate at the nominal system frequency; however, when operating at low frequency, CTs could saturate at much lower currents; this can happen even at CT nominal current. Second, there are limits of the system frequency measurements in the protective relays, which will impact the correct current magnitude estimation, and therefore, the accuracy of the protection. And finally, protective relays need full power-cycle to measure current; power-cycle will be considerably longer at lower frequency, therefore affecting fault clearance time. This paper will educate engineers on how to consider CTs and protective relay's performance at lower frequencies to ensure adequate protection. It will also explore other solutions to address impact of low frequency on the CTs and protection.
Autors: Umar Khan;Ilia Voloh;Patrick Robinson;
Appeared in: IEEE Transactions on Industry Applications
Publication date: May 2017, volume: 53, issue:3, pages: 2635 - 2641
Publisher: IEEE
 
» Constrained Turbo Product and Block-Convolutional Codes in Wireless Applications
Abstract:
Constrained interleavers are used in constrained turbo product codes (CTPCs) and constrained turbo block-convolutional (CTBC) codes. The constrained interleaver delivers an interleaver gain close to uniform interleaving while also increasing the minimum Hamming distance. In this study, new and improved single row (SR) versions of the previous codes, called SR-CTPCs and SR-CTBC codes, are introduced that have higher interleaver gain, better performance, and much more flexible frame sizes as needed in wireless applications. Compared with the WiMax and the long-term evolution standards, it is demonstrated that SR-CTPC and SR-CTBC codes perform better than those currently used in the wireless standards.
Autors: Yuan Hu;John P. Fonseka;Yu Bo;Eric M. Dowling;Murat Torlak;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: May 2017, volume: 66, issue:5, pages: 4491 - 4495
Publisher: IEEE
 
» Constraint Screening for Security Analysis of Power Networks
Abstract:
Consider a general security-constrained unit commitment (SCUC) problem for an arbitrary power network. This problem includes discrete variables corresponding to commitment parameters as well as demand and generation constraints, among others. Aside from its nonconvexity, SCUC is a large-scale problem for real-world systems due to the security constraints. The main objective of this paper is to propose an algorithm to eliminate a vast majority of linear security constraints in the high-dimensional mixed-integer SCUC problem in order to arrive at an equivalent reduced-order SCUC problem. To this end, we develop a parallel and computationally cheap algorithm for finding a minimal subset of security constraints whose satisfaction guarantees the satisfaction of all security constraints. The proposed algorithm does not depend on the unknown unit commitment parameters and allows the load forecasts to be imprecise. More specifically, a low-order model of the SCUC problem is found based on the topology of the power system, given lower and upper bounds on nodal power injections (to accommodate uncertainties in loads and generation productions), and the normal and emergency line ratings. This algorithm is tested on several power systems with as many as 5500 buses, for which each set of security constraints with millions of conditions is reduced to a minimal subset with only a few hundred conditions.
Autors: Ramtin Madani;Javad Lavaei;Ross Baldick;
Appeared in: IEEE Transactions on Power Systems
Publication date: May 2017, volume: 32, issue:3, pages: 1828 - 1838
Publisher: IEEE
 
» Construction of MDS Codes With Complementary Duals
Abstract:
A linear complementary dual (LCD) code is a linear code with complimentary dual. LCD codes have been extensively studied in literature. On the other hand, maximum distance separable (MDS) codes are an important class of linear codes that have found wide applications in both theory and practice. However, little is known about MDS codes with complimentary duals. The main purpose of this paper is to construct several classes of MDS codes with complimentary duals, i.e., LCD MDS codes, through generalized Reed-Solomon codes.
Autors: Lingfei Jin;
Appeared in: IEEE Transactions on Information Theory
Publication date: May 2017, volume: 63, issue:5, pages: 2843 - 2847
Publisher: IEEE
 
» Construction of Voronoi Diagram using the Hollow Sphere Concept
Abstract:
This paper implements an algorithm for constructing Voronoi regions using the method we call "hollow sphere". This principle uses the circle, sphere or hyper-sphere as a geometric structure taking into account an Euclidean space of an arbitrary dimension. Boris Deloné used the property of the empty circle to build the Delaunay triangulation; in our case, the same property is used to perform the validations of the hollow spheres, but without using triangles as a fundamental structure. For convenience sake, the hollow sphere as a circle so as to work in two dimensions will be explained and illustrated. However, there is no impediment to working with spheres to take the principles to a three-dimensional space. Furthermore, the properties of the hollow sphere are detailed and an algorithm of incremental construction is used with O(nlogn) time.
Autors: Netz Romero;Ricardo Barron;
Appeared in: IEEE Latin America Transactions
Publication date: May 2017, volume: 15, issue:5, pages: 950 - 958
Publisher: IEEE
 
» Contact-Force Control of a Flexible Timoshenko Arm in Rigid/Soft Environment
Abstract:
This technical note discusses a contact-force control problem of a one-link flexible arm. This flexible arm includes a Timoshenko beam, and thus we call it the flexible Timoshenko arm. The primary aim is to control the contact force at the contact point. To do so, we first apply our previously proposed force controller, which exponentially stabilizes the closed-loop system of a flexible Euler-Bernoulli arm, to the force-control problem of the flexible Timoshenko arm. We then show that our previously proposed force controller cannot exponentially stabilize the flexible Timoshenko arm. Next, we consider the flexible Timoshenko arm, which is making contact with a soft environment. By utilizing the damping force in the soft environment, as well as the controller, we try to overcome the problem. We then prove the exponential stability of the closed-loop system. Finally, we provide simulation results, and consider the validity of our force controller.
Autors: Takahiro Endo;Minoru Sasaki;Fumitoshi Matsuno;Yingmin Jia;
Appeared in: IEEE Transactions on Automatic Control
Publication date: May 2017, volume: 62, issue:5, pages: 2546 - 2553
Publisher: IEEE
 
» Content Ecosystem: Serving Diverse Interests in Our Community [From the Editor]
Abstract:
Presents the introductory editorial for this issue of the publication.
Autors: Min Wu;
Appeared in: IEEE Signal Processing Magazine
Publication date: May 2017, volume: 34, issue:3, pages: 3 - 13
Publisher: IEEE
 
» Continuous Top-k Monitoring on Document Streams
Abstract:
The efficient processing of document streams plays an important role in many information filtering systems. Emerging applications, such as news update filtering and social network notifications, demand presenting end-users with the most relevant content to their preferences. In this work, user preferences are indicated by a set of keywords. A central server monitors the document stream and continuously reports to each user the top-k documents that are most relevant to her keywords. Our objective is to support large numbers of users and high stream rates, while refreshing the top-k results almost instantaneously. Our solution abandons the traditional frequency-ordered indexing approach. Instead, it follows an identifier-ordering paradigm that suits better the nature of the problem. When complemented with a novel, locally adaptive technique, our method offers (i) proven optimality w.r.t. the number of considered queries per stream event, and (ii) an order of magnitude shorter response time (i.e., time to refresh the query results) than the current state-of-the-art.
Autors: Leong Hou U;Junjie Zhang;Kyriakos Mouratidis;Ye Li;
Appeared in: IEEE Transactions on Knowledge and Data Engineering
Publication date: May 2017, volume: 29, issue:5, pages: 991 - 1003
Publisher: IEEE
 
» Continuous-Time Marginal Pricing of Electricity
Abstract:
The current practice of discrete-time electricity pricing starts to fall short in providing an accurate economic signal reflecting the continuous-time variations of load and generation schedule in power systems. This paper introduces the fundamental mathematical theory of continuous-time marginal electricity pricing. We first formulate the continuous-time unit commitment problem as a constrained variational problem, and subsequently define the continuous-time economic dispatch (ED) problem where the binary commitment variables are fixed to their optimal values. We then prove that the continuous-time marginal electricity price equals to the Lagrange multiplier of the variational power balance constraint in the continuous-time ED problem. The proposed continuous-time marginal price is not only dependent to the incremental generation cost rate, but also to the incremental ramping cost rate of the units, thus embedding the ramping costs in calculation of the marginal electricity price. The numerical results demonstrate that the continuous-time marginal price manifests the behavior of the constantly varying load and generation schedule in power systems.
Autors: Masood Parvania;Roohallah Khatami;
Appeared in: IEEE Transactions on Power Systems
Publication date: May 2017, volume: 32, issue:3, pages: 1960 - 1969
Publisher: IEEE
 
» Control of a Direct Matrix Converter With Modulated Model-Predictive Control
Abstract:
This paper investigates the use of a model-predictive control strategy to control a direct matrix converter. The proposed control method combines the features of the classical model-predictive control and the space vector modulation technique into a modulated model-predictive control. This new solution maintains all the characteristics of model-predictive control (such as fast transient response, multiobjective control using only one feedback loop, easy inclusion of nonlinearities and constraints of the system, and the flexibility to include other system requirements in the controller), adding the advantages of working at fixed switching frequency and improving the quality of the controlled waveforms. Simulation and experimental results employing the control method to a direct matrix converter are presented.
Autors: Manjusha Vijayagopal;Pericle Zanchetta;Lee Empringham;Liliana de Lillo;Luca Tarisciotti;Patrick Wheeler;
Appeared in: IEEE Transactions on Industry Applications
Publication date: May 2017, volume: 53, issue:3, pages: 2342 - 2349
Publisher: IEEE
 
» Control of a Grid-Forming Inverter Based on Sliding-Mode and Mixed ${H_2}/{H_infty }$ Control
Abstract:
A grid-forming inverter (GFI) is an important component for the operation of an islanded microgrid. Its purpose, similar to a conventional slack bus generator, is to build up a reference voltage for other distributed generating units in the microgrid. Usually, a nested-loop proportional plus integral (PI) control structure is employed to control a GFI in a reference frame. However, conventional PI-based nested-loop control method has a deteriorative performance under parameter variations. In this paper, a novel nested-loop control strategy is proposed for control of a GFI system containing an output filter and loads. The proposed method does not require a precise model for the inverter system and can better deal with uncertainties and filter resonance without using any passive or active damping mechanisms. It utilizes a sliding-mode control in the inner current loop and a mixed optimal control in the outer voltage loop, which provides the advantages of constant switching frequency, low total harmonic distortion, robustness against parameters variations, and fast transient response. The simulation and hardware experiments presented in this paper demonstrate the proposed controller's improved transient and steady-state performance in various key criteria, over conventional PI-based nested-loop control strategy.
Autors: Zhongwen Li;Chuanzhi Zang;Peng Zeng;Haibin Yu;Shuhui Li;Jing Bian;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: May 2017, volume: 64, issue:5, pages: 3862 - 3872
Publisher: IEEE
 
» Control of Modular Multilevel Converters Under Singular Unbalanced Voltage Conditions With Equal Positive and Negative Sequence Components
Abstract:
This paper focuses on the control of Modular Multilevel Converters (MMC) for High Voltage DC (HVDC) applications during unbalanced AC grid voltage sags where positive and negative sequence voltages are equal. The control scheme is based on six arm energy regulators, six independent current controllers, and two reference calculation stages that convert the power references into grid and inner current references. Conventional inner AC currents reference calculation fails if the amplitude of the positive and the negative sequence AC grid voltages are equal, a state which is referred to in this paper as singular voltage condition. This paper discusses the types of network faults that cause this condition and proposes three different solutions to operate the converter in such scenarios. The adequacy of the proposed solutions is validated through simulations considering each of the problematic fault scenarios.
Autors: Eduardo Prieto-Araujo;Adrià Junyent-Ferré;Gerard Clariana-Colet;Oriol Gomis-Bellmunt;
Appeared in: IEEE Transactions on Power Systems
Publication date: May 2017, volume: 32, issue:3, pages: 2131 - 2141
Publisher: IEEE
 
» Control of Uncertain Sampled-Data Systems: An Adaptive Posicast Control Approach
Abstract:
This technical note proposes a discrete-time adaptive controller for the control of sampled-data systems. The design is inspired from the Adaptive Posicast Controller (APC) which was designed for time-delay systems in continuous time. Due to the performance degradation caused by digital approximation of continuous laws, together with the problem of assuming time-delays as integer multiples of sampling intervals, the benefits of APC could not be fully realized. In this technical note, these approximations/assumptions are eliminated. In addition, a disturbance observer is incorporated into the controller design which minimizes the effect of disturbances on the system. Extension to the case of uncertain input time-delay is also presented. The proposed approach is verified in simulation studies.
Autors: Khalid Abidi;Yildiray Yildiz;Anuradha Annaswamy;
Appeared in: IEEE Transactions on Automatic Control
Publication date: May 2017, volume: 62, issue:5, pages: 2597 - 2602
Publisher: IEEE
 
» Control With Minimal Cost-Per-Symbol Encoding and Quasi-Optimality of Event-Based Encoders
Abstract:
We consider the problem of stabilizing a continuous-time linear time-invariant system subject to communication constraints. A noiseless finite-capacity communication channel connects the process sensors to the controller/actuator. The sensor's state measurements are encoded into symbols from a finite alphabet, transmitted through the channel, and decoded at the controller/actuator. We suppose that the transmission of each symbol costs one unit of communication resources, except for one special symbol in the alphabet that is “free” and effectively signals the absence of transmission. We explore the relationship between the encoder's average bit-rate, its average consumption of communication resources, and the ability of the controller and encoder/decoder pair to stabilize the process. We present a necessary and sufficient condition for the existence of a stabilizing controller and encoder/decoder pair, which depends on the encoder's average bit-rate, its average resource consumption, and the unstable eigenvalues of the process. Moreover, if this condition is satisfied, a stabilizing encoding scheme can be constructed that consumes resources at an arbitrarily small rate, provided the encoder has access to a sufficiently precise clock or large memory. The paper concludes with the analysis of a simple emulation-based controller and event-based encoder/decoder pair that are easy to implement, stabilize the process, and have average bit-rate and resource consumption within a constant factor of the optimal bound.
Autors: Justin Pearson;João P. Hespanha;Daniel Liberzon;
Appeared in: IEEE Transactions on Automatic Control
Publication date: May 2017, volume: 62, issue:5, pages: 2286 - 2301
Publisher: IEEE
 
» Convergence and State Reconstruction of Time-Varying Multi-Agent Systems From Complete Observability Theory
Abstract:
We study continuous-time consensus dynamics for multi-agent systems with undirected switching interaction graphs. We establish a necessary and sufficient condition for exponential asymptotic consensus based on the classical theory of complete observability. The proof is remarkably simple compared to similar results in the literature and the conditions for consensus are mild. This observability-based method can also be applied to the case where negatively weighted edges are present. Additionally, as a by-product of the observability based arguments, we show that the nodes' initial value can be recovered from the signals on the edges up to a shift of the network average.
Autors: Brian D. O. Anderson;Guodong Shi;Jochen Trumpf;
Appeared in: IEEE Transactions on Automatic Control
Publication date: May 2017, volume: 62, issue:5, pages: 2519 - 2523
Publisher: IEEE
 
» Convex Space Building Discretization for Ray-Tracing
Abstract:
This paper describes a point-to-multipoint 3-D convex space-based ray-tracing technique. This visibility list is calculated and stored and can be reused as needed. What distinguishes our method is that the visibility list is transmitter location-independent, is a 3-D implementation, and is highly computationally efficient. The division of the building into free and filled convex spaces leads to an efficient Method of Images reflection and diffraction path generation algorithm. This technique can be used to optimize the locations of base transceivers in a highly efficient manner. The first step in producing this tool is the generation of efficient ray-tracing algorithms. The ray-tracing algorithm was specifically designed for later incorporation into a transmitter optimization algorithm. This requires a fast ray-tracing method because of its computationally intensive needs—running multiple times over a point-to-multipoint grid. Our algorithm is executed for sample building environments and then for a real building and compared with measurements to confirm its validity. It is clear that the results are in good agreement but do indicate that a highly accurate spatial modeling of the building is required.
Autors: Eamonn M. Kenny;Eamonn O. Nuallain;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: May 2017, volume: 65, issue:5, pages: 2578 - 2591
Publisher: IEEE
 
» Cooperative Caching and Transmission Design in Cluster-Centric Small Cell Networks
Abstract:
Wireless content caching in small cell networks (SCNs) has recently been considered as an efficient way to reduce the data traffic and the energy consumption of the backhaul in emerging heterogeneous cellular networks. In this paper, we consider a cluster-centric SCN with combined design of cooperative caching and transmission policy. Small base stations (SBSs) are grouped into disjoint clusters, in which in-cluster cache space is utilized as an entity. We propose a combined caching scheme, where part of the cache space in each cluster is reserved for caching the most popular content in every SBS, while the remaining is used for cooperatively caching different partitions of the less popular content in different SBSs, as a means to increase local content diversity. Depending on the availability and placement of the requested content, coordinated multi-point technique with either joint transmission or parallel transmission is used to deliver content to the served user. Using Poisson point process for the SBS location distribution and a hexagonal grid model for the clusters, we provide analytical results on the successful content delivery probability of both transmission schemes for a user located at the cluster center. Our analysis shows an inherent tradeoff between transmission diversity and content diversity in our cooperation design. We also study the optimal cache space assignment for two objective functions: maximization of the cache service performance and the energy efficiency. Simulation results show that the proposed scheme achieves performance gain by leveraging cache-level and signal-level cooperation and adapting to the network environment and user quality-of-service requirements.
Autors: Zheng Chen;Jemin Lee;Tony Q. S. Quek;Marios Kountouris;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: May 2017, volume: 16, issue:5, pages: 3401 - 3415
Publisher: IEEE
 
» Cooperative Caching Placement in Cache-Enabled D2D Underlaid Cellular Network
Abstract:
In a cache-enabled D2D underlaid cellular network, cooperation of BS caching and D2D caching can further exploit the limited storage capacity and achieve more efficient wireless resource utilization. In this complex network scenario, the closed form expression for successful transmission probability is firstly derived using stochastic geometry, to measure the proportion of users satisfying the delay guarantee. On this basis, a cooperative caching placement problem is formulated to maximize the successful transmission probability. We prove it can be transformed equivalently into a biconvex problem and then a block coordinate descent based algorithm is proposed. Simulation results demonstrate the performance gain of the proposed cooperative caching placement.
Autors: Yue Wang;Xiaofeng Tao;Xuefei Zhang;Yu Gu;
Appeared in: IEEE Communications Letters
Publication date: May 2017, volume: 21, issue:5, pages: 1151 - 1154
Publisher: IEEE
 
» Cooperative Source Node Tracking in Non-Line-of-Sight Environments
Abstract:
The accuracy of localization is highly degraded in indoor and harsh environments where source nodes either do not have connections with a sufficient number of anchor nodes due to strong attenuation or have very poor range estimates due to NLOS propagation. Cooperative localization is a technique in which the source nodes communicate not only with the anchor nodes, but also with each other. Hence, the source nodes can collect several additional measurements which significantly improve the localization performance. Although many studies have examined NLOS-degraded localization of a static node in noncooperative networks, and many others have examined the impact of cooperation for static localization, there is no work which considers cooperative tracking of mobile nodes. To address this open problem, in this work, we examine cooperative tracking, particularly in NLOS environments. More specifically, we develop a novel sensor tracking algorithm based on semidefinite programming (SDP) which has the ability to mitigate NLOS propagation. Our simulations show that the new SDP-based tracking algorithm outperforms the classic extended Kalman filter as well as the other recently proposed algorithms for noncooperative tracking in NLOS environments. We also show that the algorithm can be extended to cooperative networks, and that a substantial performance benefit is realized by cooperation.
Autors: Reza Monir Vaghefi;R. Michael Buehrer;
Appeared in: IEEE Transactions on Mobile Computing
Publication date: May 2017, volume: 16, issue:5, pages: 1287 - 1299
Publisher: IEEE
 
» Coordinated Control of Offshore Wind Farm and Onshore HVDC Converter for Effective Power Oscillation Damping
Abstract:
Damping contribution from wind farms (WFs) is likely to become a mandatory requirement as a part of the grid codes. For remote offshore WFs, connected through a voltage source converter (VSC)-based direct current link, the most convenient option for the onshore transmission system operator (TSO) is to modulate the reactive power at the onshore VSC within their own jurisdiction. In this paper, we show that supplementary control through the onshore VSC alone, although attractive for TSOs, could result in undesirable voltage variations in the onshore grid. On the other hand, modulation of active power output of the wind turbine generators (WTG) alone turns out to be inadequate due to the limited overload capability of the WTGs. Coordinated control over both onshore VSC and aggregated WF output overcomes the above limitations and is shown to be effective for power oscillation damping. A homotopy approach is used to design the coordinated controller, which can be implemented locally (at offshore WF and onshore converter site) using a decentralized architecture. This is a bilinear matrix inequality problem, which is solved by transforming these constraints into linear matrix inequality constraints. Case studies on two test systems show that the proposed controller yields similar system dynamic response as supplementary control through the WF alone.
Autors: Yousef Pipelzadeh;Nilanjan Ray Chaudhuri;Balarko Chaudhuri;Tim C. Green;
Appeared in: IEEE Transactions on Power Systems
Publication date: May 2017, volume: 32, issue:3, pages: 1860 - 1872
Publisher: IEEE
 
» Correction to “Flux Control Range Broadening and Torque Ripple Minimization of a Double Excitation Synchronous Motor”
Abstract:
In [1], an error in Fig. 2 in Section II-B is corrected. In the original figure, Fig. 2(b) was exactly the same as Fig. 2(a). The correction is shown here.
Autors: K. Hoang;L. Vido;M. Gabsi;F. Gillon;
Appeared in: IEEE Transactions on Magnetics
Publication date: May 2017, volume: 53, issue:5, pages: 1 - 1
Publisher: IEEE
 

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